JDK 9 Early Access Release Notes

Last Updated: 2017/08/17

The following is a draft of the Release Notes that will be shipped with JDK 9. Until this version releases the contents are subject to change.


New Features

Removed Features and Options

Deprecated Features and Options

Other notes


The following items describe changes to and information about this release. In some cases, the descriptions provide links to additional detailed information about an issue or a change. These Release Notes do not duplicate the descriptions of the new features and enhancements for Java SE 9 and JDK 9 provided by JDK 9 Release Notes Enhancements, What’s New in JDK 9, and JSR 379: Java SE 9: Annex 1. You should be aware of that content as well as the items described in these release notes.

The descriptions below might also identify potential compatibility issues that you could encounter when migrating to JDK 9. The Kinds of Compatibility page on the OpenJDK wiki identifies three types of potential compatibility issues for Java programs used in these descriptions:

Source: Source compatibility concerns translating Java source code into class files.

Binary: Binary compatibility is defined in The Java Language Specification as preserving the ability to link without error.

Behavioral: Behavioral compatibility includes the semantics of the code that is executed at runtime.

See the Compatibility & Specification Review (CSR) page on the OpenJDK wiki for more information about compatibility as it relates to the JDK.

Note: See the JDK 9 Migration Guide for specific compatibility issues that you might encounter when using JDK 9.

 Module System

Java SE and the JDK have been significantly updated by the introduction of the Java Platform Module System (JSR 376) and using the module system to modularize the Java SE Platform and the JDK. The compatibility issues due to the changes are documented in the "Risks and Assumptions" section of JEP 261 and also summarized here.

Source Compatibility Issues

See JDK-8142968
 New JDK Versioning Scheme

JDK 9 uses a new version string format. The most notable changes are the removal of the “1.” from the beginning of the version string and the use of 3 or more separate elements to specify major, minor, and security updates. All code that parses the value of the system properties java.version, java.specification.version, or java.vm.specification.version should be examined to ensure that it works with the new scheme. Maintainers of code that parses these properties should also be aware of the new Runtime.version() API.

Details for the new version string format can be found in JEP 223: New Version-String Scheme.

See JDK-8085822
 Use CLDR locale data by default

In JDK 9, the default locale data uses data derived from the Unicode Consortium's Common Locale Data Repository (CLDR). As a result, users may see differences in locale sensitive services behavior and/or translations. For example, CLDR does not provide localized display names for most 3-letter time zone IDs, thus the display names may be different from JDK 8 and older. The JDK continues to ship with the legacy JRE locale data and the system property java.locale.providers can be used to configure the lookup order. To enable behavior compatible with JDK 8, the system property can be set with:


For more detail, refer to the JEP 252.

See JDK-8008577
 Change default GC to G1

In JDK 9, the default garbage collector is G1 when a garbage collector is not explicitly specified. G1 provides a better overall experience for most users when compared to a throughput-oriented collector such as the Parallel GC, which was previously the default.

The options to configure the G1 collector are documented in the java command page (link). See also JEP 248 for more information on this change.

See JDK-8081607
 Modular Run-Time Images

The JDK and JRE run-time images have been restructured as documented in JEP 220. The compatibility issues due to the changes are documented in the "Risks and Assumptions" section of the JEP and also summarized here.

See JDK-8049367
 Update class file version to 53.0

When generating class files in conjunction with -target 9 (specified either explicitly or implicitly), javac will generate class files with a major version number of 53. For details of version 53 class files, see the Java Virtual Machine Specification.

The JDK classes themselves mostly use version 53 class files.

Tools or libraries that rely on ASM or other bytecode manipulation libraries may need updated versions of these libraries to work with version 53 class files.

See JDK-8148651
 Remove support for 1.5 and earlier source and target options

The javac command no longer supports -source or-target values for releases before 6/1.6. However, older class files are still readable by javac. Source code for older release can be ported to a newer source level. To generate class files usable by releases older than JDK 6, a javac from a JDK 6, 7, or 8 release family can be used.

JEP 182 documents the policy for retiring old -source and -target options.

See JDK-8011044

New Features

The following items describe some of the enhancements in Java SE 9 and JDK 9. The descriptions in these release note items often include links to documentation that describes the enhancement in greater detail. Important new features of Java SE 9 and JDK 9 are described in the What’s New in JDK 9 document.

 JEP 254 Compact Strings

In JDK 9 the internal character storage of the java.lang.String, StringBuilder and StringBuffer classes has been changed from a UTF-16 char array to a byte array plus a one-byte encoding-flag field. The new storage representation stores/encodes the characters either as ISO-8859-1/Latin-1 (one byte per character), or as UTF-16 (two bytes per character), based upon the contents of the string. The newly added encoding flag field indicates which encoding is used. This feature reduces, by 50%, the amount of space required for String objects to store the characters if the String object only contains single-byte/ latin-1 characters.

A new jvm option -XX:-CompactStrings has been introduced in JDK 9 to disable this feature, which might be worth considering when

See JDK-8054307
 Deprecation Warnings Introduced

Several APIs have been deprecated in Java SE 9. This will cause javac to emit a variety of warnings during compilation. A deprecation warning will be emitted at the use site of an API deprecated with forRemoval=false. A removal warning will be emitted at the use site of an API deprecated with forRemoval=true.

A deprecation or removal warning is a recommendation that code be migrated away from the deprecated API. A removal warning is particularly strenuous, as it is an indication that the deprecated API will generally be removed from the next major release of the platform. However, it is not always practical to migrate code immediately. Therefore, two mechanisms have been provided for controlling the warnings that are emitted by javac: command-line options and annotations in source code.

The javac command-line options -Xlint:deprecation and -Xlint:removal will enable the respective warning types, and -Xlint:-deprecation and -Xlint:-removal will disable the respective warning types. Note that removal warnings are enabled by default.

The other mechanism is to add the @SuppressWarnings("deprecation") or @SuppressWarnings("removal") annotation to the source code. This annotation can be added at the declaration of a module, class, method, field, or local variable to suppress the respective warning types emitted within that declaration.

For further information about deprecation, see JEP 277 and the documentation for the java.lang.Deprecated annotation type.

See JDK-8065614
 Unicode 8 support

The JDK 9 release includes support for Unicode 8.0. Since the release of JDK 8, which supported Unicode 6.2.0, the Unicode 8.0 introduced the following new features that are now included in JDK 9:

See JDK-8072600
 Allow use of TransmitFile on Microsoft Windows

Applications running on server editions of Microsoft Windows that make heavy use of java.nio.channels.FileChannel.transferTo may see performance improvements if the implementation uses TransmitFile. TransmitFile makes use of the Windows cache manager to provide high-performance file data transfer over sockets. The system property "jdk.nio.enableFastFileTransfer" controls whether the JDK uses TransmitFile on Microsoft Windows. It is disabled by default but can be enabled by setting the system property on the command line with -Djdk.nio.enableFastFileTransfer or -Djdk.nio.enableFastFileTransfer=true.

See JDK-8064407
 Ability to limit the capacity of buffers that can be held in the temporary buffer cache

The system property jdk.nio.maxCachedBufferSize has been introduced in 9 to limit the memory used by the "temporary buffer cache". The temporary buffer cache is a per-thread cache of direct memory used by the NIO implementation to support applications that do I/O with buffers backed by arrays in the java heap. The value of the property is the maximum capacity of a direct buffer that can be cached. If the property is not set then no limit is put on the size of buffers that are cached. Applications with certain patterns of I/O usage may benefit from using this property. In particular if an application does I/O with large multi-megabyte buffers at startup but therefore does I/O with small buffers may see a benefit to using this property. Applications that do I/O using direct buffers will not see any benefit to using this system property.

See JDK-8147468
 IBM1166 character set now available

This release adds IBM1166 character set. It provides support for cyrillic multilingual with euro for Kazakhstan. Aliases for this new character set include "cp1166","ibm1166", "ibm-1166", "1166".

See JDK-8071447
 UTF-8 based Properties Files

Properties files in UTF-8 encoding are now supported by ResourceBundle, with automatic fall back to ISO-8859-1 encoding if needed. For more detail, refer to PropertiyResourceBundle class description.

See JDK-8027607
 Provided new utility visitors supporting SourceVersion.RELEASE_9

The constructors for the utility visitors in javax.lang.model.util that correspond to the RELEASE_6 source level have been deprecated since the reference implementation regards -source 6 as obsolete. Authors of annotation processors should update their processors to support newer source versions.

See JDK-8050430
 New ManagementAgent.status diagnostic command added.

A new ManagementAgent.status diagnostic command is introduced for querying the JMX agent's status.

The status will be relayed to the user in the following form:

Agent: <enabled|disabled>
  ConnectionType: <local|remote>
  Protocol: <rmi|...>
  Host: <IP or host name>
  URL: <valid JMX connector URL>

  <name>    means an arbitrary value
  |         means 'or'
  ( and )   denote a block
  +         block repeats one or more times
  ?         block appears at most once
See JDK-8023093
 Set 32 or 64 bit JRE requirements in a JNLP file

Web Start applications can now specify requested JREs with their arch attributes, and select the first one available that matches, even if it is not the same arch (32 bit vs 64 bit) as the currently running JRE. For example, the JNLP content below would place first preference on 64 bit JDK8, and if not available, 32 bit JDK9:

<resources arch="x86_64">
     <java version="1.8"/>
<resources arch="x86">
    <java version="1.9"/>

Note that in the above example, in order to launch a 64 bit 1.8 JRE, a 64 bit 9 JRE must be installed. If only a 32 bit 9 JRE is installed, the 64 bit 1.8 JRE is unavailable.

See JDK-8055448
 osset_native_thread_name() cleanups

On platforms that support the concept of a thread name on their native threads, the java.lang.Thread.setName() method will also set that native thread name. However, this will only occur when called by the current thread, and only for threads started through the java.lang.Thread class (not for native threads that have attached via JNI). The presence of a native thread name can be useful for debugging and monitoring purposes. Some platforms may limit the native thread name to a length much shorter than that used by the java.lang.Thread, which may result in some threads having the same native name.

See JDK-7102541
 Add variant of DSA Signature algorithms that do not ASN.1 encode the signature bytes

A non-ASN.1 encoded form for DSA and ECDSA signatures has been implemented. This new signature output format concatenates the r and s values from the signature in conformance with IEEE P1363. Signature objects using this format must provide one of the following algorithm Strings to the Signature.getInstance() method:

For DSA: NONEwithDSAinP1363Format SHA1withDSAinP1363Format SHA224withDSAinP1363Format SHA256withDSAinP1363Format

For ECDSA: NONEwithECDSAinP1363Format SHA1withECDSAinP1363Format SHA224withECDSAinP1363Format SHA256withECDSAinP1363Format SHA384withECDSAinP1363Format SHA512withECDSAinP1363Format

See JDK-8042967
 Support DHE sizes up to 8192-bits and DSA sizes up to 3072-bits

Extend to support 3072-bits DH and DSA parameters generation, and pre-computed DH parameters up to 8192 bits and pre-computed DSA parameters up to 3072-bits.

See JDK-8072452
 Access ExtendedGSSContext.inquireSecContext() result through SASL

The output of ExtendedGSSContext.inquireSecContext() is now available as negotiated properties for the SASL GSSAPI mechanism using the name "com.sun.security.jgss.inquiretype.<type_name>", where "type_name" is the string form of the InquireType enum parameter in lower case. For example, "com.sun.security.jgss.inquiretype.krb5_get_session_key_ex" for the session key of an established Kerberos 5 security context.

See JDK-8044085
 Add security property to configure XML Signature secure validation mode

A new security property named jdk.xml.dsig.secureValidationPolicy has been added that allows you to configure the individual restrictions that are enforced when the secure validation mode of XML Signature is enabled. The default value for this property in the java.security configuration file is:

    disallowAlg http://www.w3.org/TR/1999/REC-xslt-19991116,\
    disallowAlg http://www.w3.org/2001/04/xmldsig-more#rsa-md5,\
    disallowAlg http://www.w3.org/2001/04/xmldsig-more#hmac-md5,\
    disallowAlg http://www.w3.org/2001/04/xmldsig-more#md5,\
    maxTransforms 5,\
    maxReferences 30,\
    disallowReferenceUriSchemes file http https,\

Please refer to the definition of the property in the java.security file for more information.

See JDK-8151893
 New APIs for jar signing

A new jdk.security.jarsigner.JarSigner API is added to the jdk.jartool module which can be used to sign a jar file.

See JDK-8056174
 accept yes/no for boolean krb5.conf settings

Besides "true" and "false", krb5.conf now also accepts "yes" and "no" for boolean-valued settings.

See JDK-8029995
 Support "include" and "includedir" in krb5.conf

The krb5.conf file now supports including other files using either the "include FILENAME" or "includedir DIRNAME" directives. FILENAME or DIRNAME must be an absolute path. The named file or directory must exist and be readable. Including a directory includes all files within the directory whose names consist solely of alphanumeric characters, dashes, or underscores. An included file can include other files but no recursion is allowed.

Also, before this change, when the same setting for a single-valued option (For example, default_realm) is defined more than once in krb5.conf, the last value was chosen. After this change, the first value is chosen. This is to be consistent with other krb5 vendors.

See JDK-8029994
 Compiler will emit a warning if deprecated javadoc tag is used without @Deprecated annotation

If the javadoc deprecated tag is used on an element without it also being deprecated using the @Deprecated annotation, the compiler will by default produce a new warning to this effect.

The new warning can be suppressed either by adding the command line option -Xlint:-dep-ann to the javac command line or by using @SuppressWarnings("dep-ann") annotation (as with any other warning-suppressing annotation, it is always a good practice to add such an annotation as close to the member being deprecated as possible).

In a future version of Java SE, the compiler may no longer treat @deprecated javadoc tag as indicating formal deprecation.

See JDK-8164073
 JShell -- New tool and API for interactive Java

Provide an interactive tool to evaluate declarations, statements, and expressions of the Java programming language, together with an API so that other applications can leverage this functionality. Adds Read-Eval-Print Loop (REPL) functionality for Java.

The jshell tool accepts "snippets" of Java code, evaluating them and immediately displaying the results. Snippets include variable and method declarations without enclosing class. An expression snippet immediately shows its value. The jshell tool also accepts commands for displaying and controlling snippets.

The jshell tool is built on the JShell API, making the evaluation of snippets of Java code available any Java program.


See JDK-8043364
 Support @-files for java command-line tool

The java launcher now supports reading arguments from "argument files" specified on the command line. It is not uncommon that the java launcher is invoked with very long command lines (a long class path for example). Many operating systems impose a limit on the length of a command line, something that "argument files" can be used to work around.

In JDK 9, java now can read arguments from specified files as they are put on the command line. See java command reference and java Command-Line Argument Files for more details.

See JDK-8027634
 Add a new launcher environment variable JDK_JAVA_OPTIONS

JDK 9 supports a new environment variable JDK_JAVA_OPTIONS to prepend options to those specified on the command line. The new environment variable has several advantages over the legacy/unsupported _JAVA_OPTIONS environment variable including the ability to include java launcher options and @file support. The new environment variable may also be useful when migrating from JDK 8 to JDK 9 for cases where new command line options (that are not supported by JDK 8) are needed.

For more details please see java launcher reference guide.

See JDK-8170832
 XPath enhancement

Java SE 9 improves the javax.xml.xpath API with new APIs that make use of modern language features to facilitate ease of use and extend support of the XPath specification.

  1. Support ANY type

javax.xml.xpath supported explicit data types defined by the XPath specification. However, it was missing the important ANY type without which the XPath API assumes that an explicit type is always known, which is not true in some circumstances. The new API now supports the ANY type so that an XPath evalution can be performed when the return type is unknown.

  1. Improved ease of use

For ease of use, four new evaluateExpression methods are added to the javax.xml.xpath.XPath and javax.xml.xpath.XPathExpression interfaces to allow specifying explicit types as follows:

When specified explicitly, the new methods return the specific types, including Boolean, Double, Integer, Long, String and org.w3c.dom.Node.

When the return type is expected to be NODESET, the new methods will return a new XPathNodes type. XPathNodes is a new interface that extends Iterable<Node> which makes it easier to use than the traditional org.w3c.dom.NodeList.

When the return type is unknown or ANY, the new methods return a new XPathEvaluationResult type. XPathEvaluationResult provides an XPathResultType enum that defines the supported types that are ANY, BOOLEAN, NUMBER, STRING, NODESET, and NODE.

See JDK-8054196
 A new property "maxXMLNameLimit" is added

A new property "maxXMLNameLimit" is added to limit the maximum size of XML names, including element name, attribute name and namespace prefix and URI. It is recommended that users set the limit to the smallest possible number so that malformed XML files can be caught quickly. For more about XML processing limits, please see The Java Tutorials, Processing Limits.

JDK-8086733 (not public)
 XML Catalog API

Java SE 9 introduces a standard XML Catalog API that supports the OASIS XML Catalogs version 1.1 standard. The API defines catalog and catalog-resolver abstractions that can be used as an intrinsic or external resolver with the JAXP processors that accept resolvers.

Existing libraries or applications that use the internal catalog API shall consider migrating to the new API in order to take advantage of the new features.

See JDK-8081248

Removed Features and Options

This section describes the features and options that were removed in JDK 9. The What’s New in JDK 9 document also identifies the removed features and options along with the JDK document in which they are described.

In addition to the features and options described in this section, JSR 379: Java SE 9: Annex 1 documents changes to the specification made between Java SE 8 and Java SE 9 that include the identification of removed features and options. You should be aware of these as well as the items described in these release notes.

 References to java.awt.peer and java.awt.dnd.peer packages were removed from the public API

All methods that refer to types defined in the java.awt.peer and java.awt.dnd.peer packages (the "peer types") were removed from the Java API in Java SE 9 . Application code which calls any such method which accepts or returns a type defined in these packages will no longer link. This is a BINARY incompatible change.

Additional information is provided here: http://mail.openjdk.java.net/pipermail/awt-dev/2015-February/008924.html

See JDK-8037739
 Remove the com.sun.image.codec.jpeg package

com.sun.image.codec.jpeg has been shipped as a non-standard API since JDK 1.2. It was always advertised as a stop-gap measure until a proper standard equivalent was provided. That replacement (javax.imageio) has been there since JDK 1.4. As a result JDK 9 finally removes the long deprecated com.sun.image.codec.jpeg API which has been flagged as intended for removal for several releases. Applications which still depend on it will need to be re-coded in order to run on JDK9.

See JDK-8038838
 JFrame.EXIT_ON_CLOSE was removed in favour of WindowConstants.EXIT_ON_CLOSE

The public static constant JFrame.EXIT_ON_CLOSE was removed in favour of WindowConstants.EXIT_ON_CLOSE.

See JDK-8073420
 Removal of rarely used sun.misc.Unsafe methods

The methods monitorEnter, monitorExit and tryMonitorEnter on sun.misc.Unsafe are removed in JDK 9. These methods are not used within the JDK itself and are very rarely used outside of the JDK.

See JDK-8054494
 Removed stopThread RuntimePermission from the default java.policy

The default java.policy no longer grants stopThread runtime permission in JDK 9.

In previous releases, untrusted code had the stopThread runtime permission by default. This allows untrusted code to call Thread::stop ( on threads other than the current one ). Having an arbitrary exception thrown asynchronously is not something that trusted code should be expected to handle gracefully. So this permission is removed by default in JDK 9. The following line is deleted from the file conf/security/java.policy : permission java.lang.RuntimePermission "stopThread";

See JDK-7067728
 "sun.lang.ClassLoader.allowArraySyntax" system property is no longer supported

The system property sun.lang.ClassLoader.allowArraySyntax was introduced as a temporary workaround to give customers time to remove their source dependency on calling ClassLoader.loadClass with the array syntax that is not supported since JDK 6. This temporary workaround is removed in JDK 9 and setting sun.lang.ClassLoader.allowArraySyntax system property will have no effect to ClassLoader.loadClass. Existing code that calls ClassLoader.loadClass to create a Class object of an array class shall be replaced with Class.forName; otherwise it will get ClassNotFoundException.

See JDK-6516909
 Remove the JDK-Internal name service provider interface and default implementation

Previous JDK releases documented how to configure java.net.InetAddress to use the JNDI DNS service provider as the name service. This mechanism, and the system properties to configure it, have been removed in JDK 9

A new mechanism to configure the use of a hosts file has been introduced.

A new system property jdk.net.hosts.file has been defined. When this system property is set, the name and address resolution calls of InetAddress, i.e getByXXX, retrieve the relevant mapping from the specified file. The structure of this file is equivalent to that of the /etc/hosts file.

When the system property jdk.net.hosts.file is set, and the specified file doesn't exist, the name or address lookup will result in an UnknownHostException. Thus, a non existent hosts file is handled as if the file is empty.

See JDK-8134577
 The lib/content-types.properties file has been removed

The lib/content-types.properties file has been removed from the Java run-time image. The lib/content-types.properties file contained the default MIME content-types table used to map content type to file extension, etc, and is used primarily by the URLConnection API. The lib/content-types.properties file was never intended to be user editable. Instead there is a system property, content.types.user.table, that allows one to define their own content types.

See JDK-8039362, for further details on the use of content.types.user.table.

See JDK-8039362
 The netdoc URL protocol Handler is removed

The netdoc protocol handler has been removed in JDK 9. Code that attempts to construct a java.net.URL with the netdoc protocol, for example "netdoc:http://foo.com/index.html" will throw a MalformedURLException.

The netdoc protocol was used to point to network documents either on the local file system or externally through an HTTP URL. This capability is essentially defunct and is not supported by Safari, Firefox, and other major browsers.

See JDK-8154234
 sun.nio.sh.PollSelectorProvider removed

The poll based SelectorProvider sun.nio.ch.PollSelectorProvider has been removed in JDK 9. It has been superseded for several releases by improved or higher performance implementations on all supported platforms.

See JDK-8142872
 Remove HTTP proxying from RMI

The mechanism of proxying RMI requests through HTTP, which was deprecated in Java SE 8, has been removed in Java SE 9. This mechanism used a web CGI script called java-rmi.cgi. This script has also been removed. The default mechanism for transmitting RMI requests is now simply a direct socket connection.

See JDK-8066750
 Remove Packer/Unpacker addPropertyChangeListener and removePropertyListener methods

The deprecated addPropertyListener and removePropertyListener methods have been removed from java.util.jar.Pack200.Packer and java.util.jar.Pack200.Unpacker. Applications that need to monitor progress of a packer or unpacker should poll the value of the PROGRESS property instead.

See JDK-8029806
 The system property sun.zip.disableMemoryMapping has been removed

The zip library implementation has been improved in JDK 9. The new java.util.zip.ZipFile implementation does not use mmap to map ZIP file central directory into memory anymore. As a result, the sun.zip.disableMemoryMapping system property is no longer needed and has been removed.

See JDK-8142508
 Remove LogManager addPropertyChangeListener and removePropertyChangeListener methods

The deprecated addPropertyListener and removePropertyListener methods have been removed from java.util.logging.LogManager. Code that relies on a listener to be invoked when logging configuration changes should use the new addConfigurationListener and removeConfigurationListener methods instead.

See JDK-8029805
 Context.APPLET is ignored when creating a JNDI InitialContext

javax.naming.Context.APPLET has been deprecated. If the environment specified when creating an InitialContext contains Context.APPLET then it is ignored. Applets with JNDI configuration in applet parameters should use the Applet.getParameter(String) method to read the parameters and use the values to create the JNDI context.

See JDK-8051422
 CodeStore service has been removed

The possibility to provide provide subclasses of jdk.nashorn.internal.runtime.CodeStore through the java.util.ServiceLoader API has been removed in JDK 9.

See JDK-8148148
 com.sun.tracing APIs are removed

The following unsupported APIs are removed:

See JDK-8062303
 SA-JDI has been removed

The Serviceability Agent (SA) Core and PID debugger Connectors have been removed in this release. It is no longer possible to use a Java Debugger to attach to a core file or process with the SA mechanism.

See JDK-8158050
 Support for IIOP transport from JMX RMI connector is removed.

The JMX RMIConnector only supports the JRMP transport in JDK 9. Support for the optional IIOP transport has been removed in this release.

JDK-8043937 (not public)
 jhat tool removed.

The experimental/unsupported jhat tool has been removed.

See JDK-8059039
 management-agent.jar is removed.

management-agent.jar has been removed. Tools that have been using the Attach API to load this agent into a running VM should be aware that the Attach API has been updated in JDK 9 to define two new methods for starting a management agent:

See JDK-8043939
 Support for serialized applets removed

Support for serialized applets has been removed. The "OBJECT" attribute of the <APPLET> tag and "object" and "java_object" applet parameter tags will no longer be recognized during applet launching, and will be ignored.

See JDK-8074161
 Remove per-compiler performance counters

Per-thread compiler performance counters have been removed because they became obsolete in the presence of more fine-grained and precise compilation events. The corresponding interface in sun.management.* has been deprecated since it will no longer provide information without the performance counters. Users can get similar or more fine-grained information via global performance counters, the event tracing API (JFR) or -XX:+PrintCompilation.

See JDK-8134607
 Remove Use486InstrsOnly flag

The -XX:+Use486InstrsOnly flag has been removed because it is no longer supported.

See JDK-6808665
 Remove EnableInvokeDynamic flag

The -XX:EnableInvokeDynamic flag has been removed because the VM does no longer support execution without invokedynamic.

See JDK-8036956
 Remove BackEdgeThreshold flag

The -XX:BackEdgeThreshold flag has been removed because it is no longer supported. Users now need to use -XX:OnStackReplacePercentage instead.

See JDK-8021770
 Remove SafepointPollOffset flag

The -XX:SafepointPollOffset flag has been removed because it was introduced only to reproduce a problem with the C1 compiler and is no longer needed.

See JDK-8031203
 Various GC combinations have now been removed

The GC combinations that were deprecated in JDK 8 have now been removed. This means that the following GC combinations no longer exist:

The command line flags that were removed are: -Xincgc, -XX:+CMSIncrementalMode, -XX:+UseCMSCompactAtFullCollection, -XX:+CMSFullGCsBeforeCompaction and -XX:+UseCMSCollectionPassing.

The command line flag -XX:+UseParNewGC no longer has any effect. ParNew can only be used with CMS and CMS requires ParNew. Thus, the -XX:+UseParNewGC flag has been deprecated and will likely be removed in a future release.

See JDK-8044022
 Remove deprecated command line flags

These internal command line flags, which have been deprecated or aliased since JDK 6, have been removed:

CMSParPromoteBlocksToClaim, ParCMSPromoteBlocksToClaim, ParallelGCOldGenAllocBufferSize, ParallelGCToSpaceAllocBufferSize, UseGCTimeLimit, CMSPermGenSweepingEnabled, ResizeTLE, PrintTLE, TLESize, UseTLE, MaxTLERatio, TLEFragmentationRatio, TLEThreadRatio

In addition to this, these internal flags have been deprecated:

CMSMarkStackSizeMax, ParallelMarkingThreads, ParallelCMSThreads, CMSMarkStackSize, G1MarkStackSize

See JDK-8061611
 VM Options AdjustConcurrency and PrintJVMWarnings are removed

The VM Options -XX:AdjustConcurrency and -XX:PrintJVMWarnings are removed from JDK 9.

The VM option -XX:AdjustConcurrency was only needed on Solaris 8/9 (when using the T1 threading library).

The VM option -XX:PrintJVMWarnings was a development option only used by unimplemented VM functions that have themselves been removed in JDK 9.

See JDK-8073861
 Remove Oracle Solaris ISA bin directories and links

On Oracle Solaris, the JDK and JRE no longer have an ISA (Instruction Specific Architecture) bin directory. The $JAVA_HOME/bin/sparcv9 and $JAVA_HOME/bin/amd64 directories, and the sym links in the directories, were present in JDK 8 to aid migration after 32-bit support was removed. Scripts or applications that rely on these locations should be updated to use $JAVA_HOME/bin.

See JDK-8029997
 lib/$ARCH directory removed from Linux and Solaris images

The lib/$ARCH directory, which used to contain native-code shared objects (.so files) for the VM and the libraries, has been removed and the contents has moved up one level into the lib/ directory.

See JDK-8066474
 JavaFX impl_* methods have been removed

Several deprecated and undocumented "impl_*" methods have been removed from JDK 9.

In prior releases, many public JavaFX classes in exported packages had public or protected implementation methods that were named with "impl_*" in the name, marked as "@Deprecated" with the stated intention of removing them, and hidden from the API documentation with the "@treatAsPrivate" javadoc tag.

These methods were never supported and were not intended to be used by applications. JavaFX applications that were using these undocumented methods will need to stop calling them.

See JDK-8144585
 JavaFX builder classes have been removed

The JavaFX builder classes, which were previously deprecated in JDK 8 with the stated intention to remove them, have been removed from JDK 9. JavaFX applications that use the builder classes should instead construct the needed scene graph objects directly and set the desired properties with the equivalent method calls.

See JDK-8092861
 AppleScript scripting engine has been removed

The AppleScript engine implementing javax.script engine API has been removed without replacement. The AppleScript engine has worked inconsistently. The services configuration (META-INF/services) file was missing and only worked by accident when installing JDK 7 or JDK 8 on systems that had Apple's version of AppleScriptEngine.jar already on the system.

See JDK-8143404
 Removal of com.apple.concurrent.Dispatch

The com.apple.concurrent.Dispatch API was a Mac-only API and was carried into JDK 7u4 with the port of Apple's JDK 6 code. This seldom-used and unsupported API has been removed in JDK 9. Developers are encouraged to use the standard java.util.concurrent.Executor and java.util.concurrent.ExecutorService APIs instead.

See JDK-8148187
 The jdk.Exported annotation has been removed

The JDK-specific annotation @jdk.Exported has been removed in JDK 9. The information that @jdk.Exported conveyed is now recorded in the exports declarations of modules. Tools that scan for this annotation should be updated to make use of the new API support in javax.lang.model and java.lang.module.

See JDK-8049422
 Remove the ExemptionMechanism.finalize() method

The javax.crypto.ExemptionMechanism.finalize() method has been removed from both the specification and the implementation.

See JDK-8159009
 Remove com.sun.security.auth.callback.DialogCallbackHandler

The com.sun.security.auth.callback.DialogCallbackHandler class has been removed. This class, which is in the JDK-specific extensions to JAAS, was deprecated in JDK 8 and previously flagged for removal.

See JDK-8029904
 rmic -Xnew option is disabled

The experimental rmic -Xnew option has been disabled for this release.

See JDK-8146299
 extcheck tool removed

The extcheck tool has been removed in this release.

See JDK-8042888
 serialver -show option is removed

The serialver -show option has been removed in this release.

See JDK-8042887
 Removal of native2ascii tool

native2ascii tool is removed in JDK 9. JDK 9 supports UTF-8 based properties resource bundles (see JEP 226) and the conversion for UTF-8 based properties resource bundles to ISO-8859-1 is no longer needed.

See JDK-8074431
 Remove Launch-Time JRE Version Selection

The Launch-Time JRE Version Selection also known as Multiple JRE or mJRE functionality will no longer be available with the java launcher. This means the java launcher will not invoke another JRE version, and will exit with an error.

The presence of "-version:x.y.z", "-jre-restrict-search" and "-jre-no-restrict-search" on the java launcher's command-line will cause it to exit with an error message. The environment variable "JRE_VERSION_PATH" will be ignored.

The Java Archive (jar) manifest entry "JRE-version" will cause the java launcher to emit a warning, and "JRE-Restrict-Search" will be ignored.

See JDK-8050071
 Visual VM removed in JDK 9

Visual VM is a tool that provides information about code running on a Java Virtual Machine. It was provided with Oracle JDK 6, Oracle JDK 7, and Oracle JDK 8.

Starting from JDK 9, the tool (jvisualvm) is no longer included in Oracle JDK. Users can still download the tool from the official project website at https://visualvm.github.io

See JDK-8160881

Deprecated Features and Options

This section describes the deprecated features and options in JDK 9. Features and options that have been identified as deprecated in JDK 9 are subject to removal from future versions of the JDK and should only be used with that possibility in mind.

Other sources of information about the APIs, features, and options deprecated in Java SE 9 and JDK 9 include:

What’s New in JDK 9 - Identifies deprecated APIs, features, and options as well as provides links to the documents where they are described in detail.

Deprecated API page (API specification) - Identifies all deprecated APIs including those deprecated in Java SE 9.

JSR 379: Java SE 9: Annex 1 - Documents changes to the specification made between Java SE 8 and Java SE 9 that include the identification of deprecated APIs and features not described here.

You should be aware of the contents in these documents as well as the items described in these release notes.

The descriptions of deprecated APIs might include references to the deprecation warnings of forRemoval=true and forRemoval=false. The forRemoval=true text indicates that a deprecated API might be removed from the next major release. The forRemoval=false text indicates that a deprecated API is not expected to be removed from the next major release but might be removed in some later release.

Note: JEP 277: Enhanced Deprecation provides a detailed description of JDK 9's updated deprecation policy. You should be aware of the updated policy described in this document.

 AppletViewer is deprecated

The AppletViewer tool was deprecated as a part of "JEP C161: Deprecate the Java Plug-in", and its use isn't recommended,

More information about AppletViewer: http://docs.oracle.com/javase/8/docs/technotes/tools/windows/appletviewer.html

JDK-8074165 (not public)
 Deprecate sun.misc.Unsafe.defineClass

The method sun.misc.Unsafe.defineClass is deprecated for removal. Use the method java.lang.invoke.MethodHandles.Lookup.defineClass to define a class to the same class loader and in the same runtime package and protection domain of a given Lookup's lookup class.

See JDK-8181442
 Deprecation of Boxed Primitive Constructors

Classes Boolean, Byte, Short, Character, Integer, Long, Float, and Double are "box" classes that correspond to primitive types. The constructors of these classes have been deprecated.

Given a value of the corresponding primitive type, it is generally unnecessary to construct new instances of these box classes. The recommended alternatives to construction are autoboxing or the valueOf static factory methods. In most cases, autoboxing will work, so an expression whose type is a primitive can be used in locations where a box class is required. This is covered in the Java Language Specification, section 5.1.7, "Boxing Conversion." For example, given List<Integer> intList, the code to add an Integer might be as follows:

    intList.add(new Integer(347));

This can be replaced with:


Autoboxing should not be used in places where it might affect overload resolution. For example, there are two overloads of the List.remove method:

    List.remove(int i)        // removes the element at index i
    List.remove(Object obj)   // removes an element equal to obj

The code to remove the Integer value 347 might be as follows:

    intList.remove(new Integer(347));

If this code is changed in an attempt to use autoboxing:


This will not remove the Integer value 347, but instead it will resolve to the other overloaded method, and it will attempt to remove the element at index 347.

Autoboxing cannot be used in such cases. Instead, code should be changed to use the valueOf static factory method:


Autoboxing is preferable from a readability standpoint, but a safer transformation is to replace calls to the box constructors with calls to the valueOf static factory method.

Using autoboxing or the valueOf method reduces memory footprint compared to the constructors, as the integral box types will generally cache and reuse instances corresponding to small values. The special case of Boolean has static fields for the two cached instances, namely Boolean.FALSE and Boolean.TRUE.

With the exception of Character, the box classes also have constructors that take a String argument. These parse and convert the string value and return a new instance of the box class. A valueOf overload taking a String is the equivalent static factory method for this constructor. Usually it's preferable to call one of the parse methods (Integer.parseInt, Double.parseDouble, etc.) which convert the string and return primitive values instead of boxed instances.

See JDK-8065614
 Deprecate Object.finalize

The java.lang.Object.finalize method has been deprecated. The finalization mechanism is inherently problematic and can lead to performance issues, deadlocks, and hangs. The java.lang.ref.Cleaner and java.lang.ref.PhantomReference provide more flexible and efficient ways to release resources when an object becomes unreachable. For further information, please see the java.lang.Object.finalize method specification.

See JDK-8165641
 Ability to double-jar class files is deprecated

The ability to double-jar (jarjar) a set of class files in Java deployment technologies has been deprecated. The following warning will be issued if a jarjar file is downloaded:

"WARNING: A jarjar file has been loaded. Jarjar files are deprecated and will be removed in a future Java release. This application may not function properly in the future. Jarjar file URL: {URL}"

JDK-8074157 (not public)
 Java Packager '-makeall' argument deprecated

The '-makeall' argument of the Java Packager's command line interface has been deprecated. Use of '-makeall' will result in a warning. In lieu of the '-makeall' command, independent commands should be issued to perform compilation, createjar, and deploy, steps.

See JDK-8160835
 Deprecation of common DOM APIs

The com.sun.java.browser.plugin2.DOM, and sun.plugin.dom.DOMObject APIs have been deprecated and will be removed in a future release of Java. Applications can use netscape.javascript.JSObject to manipulate the DOM.

JDK-8074162 (not public)
 AutoGCSelectPauseMillis has been deprecated

This option was deprecated in JDK 9, following the deprecation of the -XX:+UseAutoGCSelectPolicy option.

See JDK-8166461
 JEP C175 Deprecate the Concurrent Mark Sweep (CMS) Garbage Collector in Oracle builds

The CMS garbage collector was deprecated in JDK 9. For more information, see -XX:+UseConcMarkSweepGC

JDK-8162744 (not public)
 UseAutoGCSelectPolicy has been deprecated

This option was deprecated in JDK 9, along with the -XX:AutoGCSelectPauseMillis option.

See JDK-8166461
 Deprecate the flag -XXExplicitGCInvokesConcurrentAndUnloadsClasses

The flag -XX:ExplicitGCInvokesConcurrentAndUnloadsClasses has been deprecated and will be removed in a future release. A user can enable the same functionality by setting the two flags -XX:+ExplicitGCInvokesConcurrent and -XX:+ClassUnloadingWithConcurrentMark.

See JDK-8170388
 Deprecate FlatProfiler

The VM Option "-Xprof" is deprecated in JDK 9 and will be removed in a future release. The option provides some profiling data for code being executed to standard output. Better data can be gathered with other tools such as Java Flight Recorder and therefore "-Xprof" will no longer be available in a future release.

See JDK-8176098
 Deprecate HostServices.getWebContext method with forRemoval=true

The HostServices.getWebContext method is deprecated in JDK 9 and is marked as forRemoval=true indicating that it will be removed in a future version of the JDK. Applets are deprecated in JDK 9, and this method is only used when running an FX application as an Applet in a browser.

See JDK-8156963
 VP6 video and FXM/FLV container are deprecated

Support for VP6 video encoding format and FXM/FLV container are deprecated in JavaFX Media and it will be removed in a future release. Users encouraged to use H.264/AVC1 in MP4 container or HTTP Live Streaming instead.

See JDK-8134330
 Deprecate pre-1.2 SecurityManager methods and fields with forRemoval=true

The following pre-1.2 deprecated java.lang.SecurityManager methods and fields have been marked with forRemoval=true: the inCheck field, and the getInCheck, classDepth, classLoaderDepth, currentClassLoader, currentLoadedClass, inClass, and inClassLoader methods. This field and methods should no longer be used and are subject to removal in a future version of Java SE.

See JDK-8161506
 Deprecate the java.security.acl API

The java.security.acl API has been deprecated. The classes in this package should no longer be used. The java.security package contains suitable replacements. See Policy and related classes for details.

See JDK-8157847
 Deprecate the com.sun.jarsigner package

The com.sun.jarsigner package is now deprecated. This includes the ContentSigner class, the ContentSignerParameters interface, and the jarsigner command's "-altsigner" and "-altsignerpath" options.

See JDK-8076535
 Deprecate security APIs that have been superseded

The classes and interfaces in the java.security.acl and javax.security.cert packages have been superseded by replacements for a long time and are deprecated in JDK 9. Two methods javax.net.ssl.HandshakeCompletedEvent.getPeerCertificateChain() and javax.net.ssl.SSLSession.getPeerCertificateChain() are also deprecated since they return the javax.security.cert.X509Certificate type.

See JDK-8073430
 Deprecate the javax.security.cert API

The javax.security.cert API has been deprecated. The classes in this package should no longer be used. The java.security.cert package contains suitable replacements.

See JDK-8157712
 Deprecate methods that reference javax.security.cert APIs

The java.net.ssl.HandshakeCompletedEvent.getPeerCertificateChain and java.net.ssl.SSLSession.getPeerCertificateChain methods have been deprecated. New applications should use the getPeerCertificates method instead.

See JDK-8161898
 Deprecate policytool

The policytool security tool is moved into the jdk.policytool module and has been deprecated.

See JDK-8147400
 The old standard doclet is deprecated and will be removed in a future release

The standard doclet is the doclet in the JDK that produces the default HTML-formatted API output. The version that was available in previous releases (com.sun.tools.doclets.standard.Standard) has been replaced by a new version (jdk.javadoc.doclet.Standard). The old version is now deprecated and is subject to removal in a future version of Java SE. For more details, see JEP 221. For more details on the new Doclet API, see the jdk.javadoc module.

See JDK-8177484
 Options -d32 and -d64 are deprecated

The java launcher's data model switches, -d32 and -d64, were used primarily on Solaris platforms. With the removal of 32-bit JDK/JRE on Solaris in JDK8, these options are now obsolete and will be removed in a future release, causing the launcher to fail with an invalid option.

JDK-8168826 (not public)

Other notes

 No longer possible to create System L&F via reflection

Some applications have been used core reflection to instantiate JDK internal Swing L&Fs, i.e system L&Fs such as The Windows L&F : Class.forName(" com.sun.java.swing.plaf.windows.WindowsLookAndFeel")

These classes are internal to the JDK and applications should have always treated them as such.

As of JDK 9 whether these are accessible to applications depends on the configuration of the Java Platform Module System and the value of the --illegal-access setting. By default in JDK 9 its value is "permit", but this is expected to change to "deny" in a future release.

Applications which need to create a system L&F must migrate to use the new method : javax.swing.UIManager.createLookAndFeel(String name);

See JDK-8136366
 Restrict javax.imageio.spi.ServiceRegistry to ImageIO types

Since Java SE 1.4 javax.imageio.spi.ServiceRegistry provided a facility roughly equivalent to the Java SE 1.6 java.util.ServiceLoader. This image i/o facility is now restricted to supporting SPIs defined as part of javax.imageio. Applications which use it for other purposes need to be re-coded to use ServiceLoader.

See JDK-8068749
 Value of java.awt.font.OpenType.TAG_OPBD is incorrect

The value of the static final int field java.awt.font.OpenType.TAG_OPBD was incorrect

It was erroneously using the same value as TAG_MORT 0x6D6F7274UL and it has been changed to the correct 0x6F706264UL

Although this is strictly an incompatible binary change the likelihood of any practical impact on applications is near zero. The opbd table is used only in AAT fonts: https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6opbd.html and as such is likely to be extremely rare in the wild as they are natively understood only by MacOS and iOS. This table is not critical to rendering of text by Java or anything else. As such nothing goes looking for the table and nothing inside JDK utilises any part of this class.

Nor does the JDK provide anyway at all to utilise these values directly - no Java API exists that accepts them. The class will not become useful without additional Java API that has not been added to date.

Even if an application were to use it by passing the Java field's value to some custom native code to look up a table then it is likely to return "null" both before and afterward since

  1. the opbd table is extremely rare.
  2. the "mort" table that the old value located is already replaced in all fonts on OSX by the "morx" table.

A representative sampling of 6 OS X fonts found none of them to have either table

See JDK-8077584
 Some platforms may not support showing the user-specified title in a file dialog.

There are some platforms like Mac OS X 10.11 that may not support showing the user-specified title in a file dialog.

The following description is added to the java.awt.FileDialog class constructors and setTitle(String) method: "Note: Some platforms may not support showing the user-specified title in a file dialog. In this situation, either no title will be displayed in the file dialog's title bar or, on some systems, the file dialog's title bar will not be displayed".

JDK-8138674 (not public)
 Three com.sun.java.accessibility.utils internal fields are now private

Three static fields exposing event listener instances whose types are internal and intended use was internal are now made private. These are very unlikely to have been used by many applications as until recently they were shipped only as an unbundled component.

See JDK-8167182
 Trackpad scrolling of text on OS X 10.12 Sierra is very fast

The MouseWheelEvent.getWheelRotation() method returned rounded native NSEvent deltaX/Y events on Mac OS X. The latest macOS Sierra 10.12 produces very small NSEvent deltaX/Y values so rounding and summing them leads to the huge value returned from the MouseWheelEvent.getWheelRotation(). The JDK-8166591 fix accumulates NSEvent deltaX/Y and the MouseWheelEvent.getWheelRotation() method returns non-zero values only when the accumulated value exceeds a threshold and zero value. This is compliant with the MouseWheelEvent.getWheelRotation() specification:


Returns the number of "clicks" the mouse wheel was rotated, as an integer. A partial rotation may occur if the mouse supports a high-resolution wheel. In this case, the method returns zero until a full "click" has been accumulated.

For the precise wheel rotation values, use the MouseWheelEvent.getPreciseWheelRotation() method instead.

See JDK-8166591
 Tab key should move to focused button in a button group

The focus behavior of Swing toggle button controls (JRadioButton and JCheckBox) changed when they belonged to a button group. Now, if the input focus is requested to any toggle button in the group through either focus traversal or window activation, the currently selected toggle button is focused regardless of the focus traversal policy used in the container. If the selected toggle button is not eligible to be a focus owner, the focus is set according to the focus traversal policy.

See JDK-8074883
 Closing the ProgressMonitor dialog

The ProgressMonitor dialog can be closed in following ways :

  1. 'Cancel' button is pressed
  2. Dialog Close button is pressed
  3. Escape key is pressed

If the ProgressMonitor dialog is closed, ProgressMonitor.isCanceled() method used to return 'true' in only cases (1) and (2) above. This fix corrects the behavior where ProgressMonitor.isCanceled() method will return 'true' in case the ProgressMonitor dialog is closed by pressing Escape key.

There is low compatibility impact of this fix : This change may impact user code that (incorrectly) assumes ProgressMonitor.isCanceled() will return false even if the ProgressMonitor dialog is closed as a result of pressing Escape key. Also, with this change, now there is no way to get the ProgressMonitor dialog out of way whilst having progress continue.

See JDK-8065861
 Remove pathname canonicalization from FilePermission

Prior to JDK 9, creating a FilePermission object canonicalized its pathname, and the implies and equals methods were based on this canonicalized pathname. For example, if "file" and "/path/to/current/directory/file" point to the same file in the file system, two FilePermission objects from these pathnames are equal and imply each other if their actions are also the same.

In JDK 9, the pathname will not be canonicalized by default. This means two FilePermission objects will not equal each other if one uses an absolute path and the other a relative path, or one uses a symbolic link and the other the target, or one uses a Windows long name and the other a DOS-style 8.3 name, even if they point to the same file in the file system.

A compatibility layer has been added to ensure that granting a FilePermission for a relative path will still permit applications to access the file with an absolute path (and vice versa). This works for the default Policy provider and the limited doPrivileged (http://openjdk.java.net/jeps/140) calls. For example, although a FilePermission on a file with a relative pathname of "a" no longer implies a FilePermission on the same file with an absolute pathname of "/pwd/a" (suppose "pwd" is the current working directory), granting code a FilePermission to read "a" allows that code to also read "/pwd/a" when a Security Manager is enabled. This compatibility layer does not cover translations between symbolic links and targets, or Windows long names and DOS-style 8.3 names, or any other different name forms that can be canonicalized to the same name.

A system property named jdk.io.permissionsUseCanonicalPath has been introduced. When it is set to "true", FilePermission will canonicalize its pathname as it did before JDK 9. The default value of this property is "false".

An experimental system property named jdk.security.filePermCompat has also been introduced. When set to "true", the compatibility layer described above will also apply to third-party Policy implementations. The default value of this property is "false".

See JDK-8164705
 CharArrayReader, PushbackReader, and StringReader may now block in close()

The java.io classes CharArrayReader, PushbackReader, and StringReader might now block in close() if there is another thread holding the Reader.lock lock.

The read() method of these classes could previously throw a NullPointerException if the internal state of the instance had become inconsistent. This was caused by a race condition due to close() not obtaining a lock before modifying the internal state of the Reader. This lock is now obtained which can result in close() blocking if another thread simultaneously holds the same lock on the Reader.

See JDK-8143394
 Class.getSimpleName() reads from the InnerClasses attribute

Class.getSimpleName() was changed to use the name recorded in the InnerClasses attribute of the class file. This change may affect applications which generate custom bytecode with incomplete or incorrect information recorded in the InnerClasses attribute.

See JDK-8057919
 java.lang.ref.Reference.enqueue method clears the reference object before enqueuing

java.lang.ref.Reference.enqueue method clears the reference object before it is added to the registered queue. When the enqueue method is called, the referent is cleared and get() method will return null in JDK 9.

Typically when a reference object is enqueued, it is expected that the referent is no longer referenced and is cleared explicitly via the clear method to avoid memory leak. In other words the get method is expected not to be called in common cases once the enqueuemethod is called. In the case when the get method from an enqueued reference object and existing code attempts to access members of the referent object, NullPointerException may be thrown. Such code will need to be updated.

See JDK-8175797
 Spec update of ClassLoader.getResourceXXXXX() @throws NPE

The spec of the following java.lang.ClassLoader methods for locating a resource by name are updated to throw NullPointerException when the specified name is null:


Custom class loader implementations that override these methods should be updated accordingly to conform to this spec.

See JDK-8136831
 Change SecurityManager checkTopLevelWindow, checkSystemClipboard, checkAccessAwtEventQueueAccess to check AllPermission

The deprecated checkTopLevelWindow, checkSystemClipboard, and checkAccessAwtEventQueueAccess in java.lang.SecurityManager have been changed to check AllPermission, they no longer check AWTPermission. Libraries that invoke these SecurityManager methods to do permission checks may require users of the library to change their policy files.

See JDK-8029886
 Phantom references are automatically cleared as soft and weak references

This enhancement changes phantom references to be automatically cleared by the garbage collector as soft and weak references.

An object becomes phantom reachable after it has been finalized. This change may cause the phantom reachable objects to be GC'ed earlier - previously the referent is kept alive until PhantomReference objects are GC'ed. This potential behavioral change might only impact existing code that would depend on PhantomReference being enqueued rather than when the referent be freed from the heap.

See JDK-8071507
 MethodHandles.bind obeys protected access rules

The method java.lang.invoke.MethodHandles.bind has been fixed to correctly obey the access rules when binding a receiver object to a protected method.

See JDK-8177146
 invokedynamic implementation should not wrap Errors

The invokedynamic byte code instruction is no longer specified by the Java Virtual Machine Specification to wrap any Throwable thrown during linking in java.lang.invoke.BootstrapMethodError, which is then thrown to the caller.

If during linking an instance of Error, or a subclass of, is thrown then that Error is no longer wrapped and is thrown directly to the caller. Any other instance of Throwable, or subclass of, is still wrapped in java.lang.invoke.BootstrapMethodError.

This change in behaviour ensures that errors such as OutOfMemoryError or ThreadDeath are thrown unwrapped and may be acted on or reported directly, thereby enabling more uniform replacement of byte code with an invokedynamic instruction whose call site performs the same functionality as the replaced byte code (and may throw the same errors).

See JDK-8166974
 java.lang.invoke.LambdaMetafactory cannot be constructed

A behavioural change has been made to class java.lang.invoke.LambdaMetafactory so that it is no longer possible to construct an instance. This class only has static methods to create "function objects" (commonly utilized as bootstrap methods) and should not be instantiated. The risk of source and binary incompatibility is very low; analysis of existing code bases found no instantiations.

See JDK-8177153
 Class.getMethod and Class.getMethods more accurately follow inheritance rules

The javadoc for the Class.getMethod and Class.getMethods refer to the definition of inheritance in the Java Language Specification. Java SE 8 changed these rules in order to support default methods and reduce the number of redundant methods inherited from superinterfaces (see JLS 8, 8.4.8).

Class.getMethod and Class.getMethods were not updated with the 8 release to match the new inheritance definition (both may return non-inherited superinterface methods). The implementation has now been changed to filter out methods that are not members of the class.

See JDK-8029459
 Annotation toString output not reusable for source input

The exact toString output of an annotation is deliberately not specified; from java.lang.annotation.Annotation.toString():

Returns a string representation of this annotation. The details of the representation are implementation-dependent [...]

Previously, the toString format of an annotation did not output certain information in a way that would be usable for a source code representation of an annotation, string values were not surrounded by double quote characters, array values were surrounded by brackets ("[]") rather than braces ("{}"), etc.

As a behavioral change, the annotation output has been updated to be faithful to a source code representation of the annotation.

See JDK-8162817
 Executable.getAnnotatedReceiverType() is sensitive to the kind of Executable

The behavior of getAnnotatedReceiverType() has been clarified to return an empty AnnotatedType object only for a method/constructor which could conceptually have a receiver parameter but does not have one at present. (Since there is no receiver parameter, there are no annotations to return.) In addition, the behavior of getAnnotatedReceiverType() has been clarified to return null for a method/constructor which cannot ever have a receiver parameter (and therefore cannot have annotations on the type of a receiver parameter): static methods, and constructors of non-inner classes. Incompatibility: Behavioral

See JDK-8044629
 Updates to java.lang.reflect.Field.get(), Field.get{primitive}() and java.lang.reflect.Method.invoke()

java.lang.reflect.Field.get(), Field.get{primitive}() and java.lang.reflect.Method.invoke() have been updated to use the primitive wrapper classes' valueOf() (for example Integer.valueOf()) instead of always creating new wrappers with "new" (for example new Integer()) after the reflection libraries have (potentially) optimised the Field/Method instance. This can affect applications that depended on two wrappers being != while still being .equals().

See JDK-5043030
 Platforms without multicasting support

In Java SE 9 the requirement to support multicasting has been somewhat relaxed, in order to support a small number of platforms where multicasting is not available. The specification for the java.net.MulticastSocket::joinGroup and the java.nio.channels.MulticastChannel::join methods has been updated to indicate that an UnsupportedOperationException will be thrown if invoked on a platform that does not support multicasting.

There is no impact to Oracle JDK platforms, since they do support multicasting.

See JDK-8157166
 HttpCookie parsing only works for response cookie headers

The current implementation of java.net.HttpCookie can only be used to parse cookie headers generated by a server and sent in a HTTP response as a Set-Cookie or Set-Cookie2 header. It does not support parsing of client generated cookie headers.

This is not completely clear from the API documentation of that class. The documentation could be updated to make the current behavior clearer, or preferably, the implementation could be updated to support both behaviors in a future release.

See JDK-8129622
 Modified HttpURLConnection behavior when no suitable proxy is found

The behavior of HttpURLConnection when using a ProxySelector has been modified with this JDK release. HttpURLConnection used to fall back to a DIRECT connection attempt if the configured proxy(s) failed to make a connection. This release introduces a change whereby no DIRECT connection will be attempted in such a scenario. Instead, the HttpURLConnection.connect() method will fail and throw an IOException which occurred from the last proxy tested.

See JDK-8161016
 java.nio.channels.FileLock constructors don't throw NPE if the channel argument is null

The java.nio.channels.FileLock constructors will now throw a NullPointerException if called with a null Channel parameter. To avoid an unexpected behavior change, subclasses of FileLock should therefore ensure that the Channel they pass to the superclass constructor is non-null.

See JDK-6880737
 The SecurityException throws clauses of the java.nio.file.Files methods newBufferedWriter() and write() now indicate that the exception might arise from a "delete" permission check

The sentence

"The SecurityManager.checkDelete(String) method is invoked to check delete access if the file is opened with the DELETE_ON_CLOSE option."

was appended to the verbiage of the SecurityException throws clause in the specifications of the newBufferedWriter() and write() methods of java.nio.file.Files.

See JDK-8065109
 RMI server-side multiplex protocol has been disabled

The RMI multiplex protocol is disabled by default. It can be re-enabled by setting the system property "sun.rmi.transport.tcp.enableMultiplexProtocol" to "true".

See JDK-8158963
 Changing the boundaries specified by ChronoField.EPOCH_DAY

Boundaries specified by java.time.temporal.ChronoField.EPOCH_DAY have been corrected to match the epoch day of LocalDate.MIN and LocalDate.MAX

See JDK-8160681
 Return unmodifiable set of zone IDs to optimize ZoneIdPrinterParser

The performance of java.time.zone.ZoneRulesProvider.getAvailableZoneIds() is improved by returning an unmodifiable set of zone ids; previously the set was modifiable.

See JDK-8066291
 The implementation of the clock returned by system factory methods in java.time.Clock has increased the resolution

The Java SE 8 specification for java.time.Clock states that ''The system factory methods provide clocks based on the best available system clock. This may use System.currentTimeMillis(), or a higher resolution clock if one is available.'' In JDK 8 the implementation of the clock returned was based on System.currentTimeMillis(), and thus has only a millisecond resolution. In JDK 9, the implementation is based on the underlying native clock that System.currentTimeMillis() is using, providing the maximum resolution available from that clock. On most systems this can be microseconds, or sometimes even tenth of microseconds.

An application making the assumption that the clock returned by these system factory methods will always have milliseconds precision and actively depends on it, may therefore need to be updated in order to take into account the possibility of a greater resolution, as was stated in the API documentation. It is also worth noting that a new Clock.tickMillis(zoneId) method has been added to allow time to be obtained at only millisecond precision - see: http://download.java.net/java/jdk9/docs/api/java/time/Clock.html#tickMillis-java.time.ZoneId-.

See JDK-8068730
 De-synchronize java.util.Properties getter methods

java.util.Properties is a subclass of the legacy Hashtable class, which synchronizes on itself for any access. System properties are stored in a Properties object. They are a common way to change default settings, and sometimes must be read during classloading.

System.getProperties() returns the same Properties instance accessed by the system, which any application code might synchronize on. This situation has lead to deadlocks in the past, such as 6977738.

The Properties class has been updated to store its values in an internal ConcurrentHashMap (instead of using the inherited Hashtable mechanism), and its getter methods and legacy Enumerations are no longer synchronized. This should reduce the potential for deadlocks. It also means that since Properties' Iterators are now generated by ConcurrentHashMap, they don't fail-fast - ConcurrentModificationExceptions are no longer thrown.

See JDK-8029891
 Default locale in java.util.Formatter related classes.

The specification of the default locales used in Formatter related classes has been clarified to designate the default locale for formatting (Locale.Category.FORMAT).

See JDK-8146156
 java.util.UUID#fromString(String) now throws IllegalArgumentException if the parameter is too long

As part of the fix for JDK-8006627, a check of the String parameter of java.util.UUID.fromString(String) was added which will result in an IllegalArgumentException being thrown if the length of the parameter is greater than 36.

See JDK-8006627
 Properties loadFromXML/storeToXML methods do not support all encodings

java.util.Properties defines the loadFromXML and storeToXML methods for Properties stored in XML documents. XML specifications only require XML processors to read entities in UTF-8 and UTF-16 and the API docs for these methods only require an implementation to support UTF-8 and UTF-16. The implementation of these methods has changed in JDK 9 to use a smaller XML parser which may impact applications that have been using these methods with other encodings. The new implementation does not support all encodings that the legacy implementation had support for, in particular it does not support UTF-32/UCS-4, IBM* or x-IBM-* encodings. For maximum portability, applications are encouraged to use UTF-8 and UTF-16.

See JDK-8042889
 java.util.prefs.Preferences now disallows the use of any String containing the null control character

The specification of the class java.util.prefs.Preferences was modified to disallow the use of any String containing the null control character, code point U+0000, in any String used as the key or value parameter in any of the abstract put*(), get*(), and remove methods. If such a character is detected, an IllegalArgumentException shall be thrown.

The specification of the class java.util.prefs.AbstractPreferences was modified according to the corresponding change in its superclass java.util.prefs.Preferences to disallow the use of any String containing the null control character, code point U+0000, in any String used as the key or value parameter in any of the put*(), get*(), and remove() method implementations. These method implementations were modified to throw an IllegalArgumentException upon encountering such a character in a key or value String in these contexts. Also, the class specification was modified to correct the erroneous reference to the flush() and sync() methods as returning a boolean value when they are in fact void.

See JDK-8075156
 Fork/Join common pool threads return the system class loader as their thread context class loader

In Java SE 9, threads that are part of the fork/join common pool will always return the system class loader as their thread context class loader. In previous releases, the thread context class loader may have been inherited from whatever thread causes the creation of the fork/join common pool thread, e.g. by submitting a task. An application cannot reliably depend on when, or how, threads are created by the fork/join common pool, and as such cannot reliably depend on a custom defined class loader to be set as the thread context class loader.

See JDK-8172726
 java.util.zip.ZipFile.getEntry() now always returns the ZipEntry instance with a '/' ended entry name for directory entry

java.util.zip.ZipEntry API doc specifies "A directory entry is defined to be one whose name ends with a '/'". However, in previous JDK releases java.util.zip.ZipFile.getEntry(String entryName) may return a ZipEntry instance with an entry name that does not end with '/' for an existing zip directory entry when the passed in argument entryName does not end with a '/' and there is a matching zip directory entry with name entryName + '/' in the zip file. With JDK 9 the name of the ZipEntry instance returned from java.util.zip.ZipFile.getEntry() always ends with '/' for any zip directory entry.

See JDK-6233323
 Deflater issue with zlib 1.2.11

zlib issue #275 tracks an issue in zlib 1.2.11 that may impact applications using the java.util.zip.Deflater API when this version of zlib is installed (Ubuntu 17.04 for example). Specifically, it may impact code that changes the compression level or strategy and then resets the deflater. More details can be found in JDK-8184306. The JDK includes a patched version of zlib on Microsoft Windows so this issue does not impact that platform.

See JDK-8185101
 JDK 9 rejects zip files where the modified day or month is 0

The ZipFile implementation has changed significantly in JDK 9 to improve reliability. A consequence of these changes is that the implementation now rejects ZIP files where the month or day in a MS-DOS date/time field is 0. While technically invalid, these ZIP files were not rejected in previous release. A future release will address this issue.

See JDK-8184940
 Precision of time stamps in java.util.logging.LogRecord has been increased

LogRecord now stores the event time in the form of a java.time.Instant. XMLFormatter DTD is upgraded to print the new higher time resolution.

In Java SE 9 java.util.logging is updated to use java.time instead of System.currentTimeMillis() and java.util.Date. This allows for higher time stamp precision in LogRecord.

As a consequence, the implementation of the methods getMillis() and setMillis(long) in java.util.logging.LogRecord has been changed to use java.lang.Instant, and the method setMillis(long) has been deprecated in favor of the new method LogRecord.setInstant(java.time.Instant). The java.util.logging.SimpleFormatter has been updated to pass a java.time.ZonedDateTime object instead of java.util.Date to String.format. The java.util.logging.XMLFormatter has been updated to print a new optional <nanos> XML element after the <millis> element. The <nanos> element contains a nano seconds adjustment to the number of milliseconds printed in the <millis> element. The XMLFormatter will also print the full java.time.Instant in the <date> field, using the java.time.format.DateTimeFormatter.ISO_INSTANT formatter.

Compatibility with previous releases:

The LogRecord serial form, while remaining fully backward/forward compatible, now contains an additional serial nanoAdjustment field of type int, which corresponds to a nano seconds adjustment to the number of milliseconds contained in the serial millis field. If a LogRecord is serialized and transmitted to an application running on a previous release of the JDK, the application will simply see a LogRecord with a time truncated at the millisecond resolution. Similarly, if a LogRecord serialized by an application running on a previous release of the JDK, is transmitted to an application running on Java SE 9 or later, only the millisecond resolution will be available.

Applications that parse logs produced by the XMLFormatter, and which perform validation, may need to be upgraded with the newer version of the logger.dtd, available in the appendix A of the Logging Overview. In order to mitigate the compatibilty risks, the XMLFormatter class (and subclasses) can be configured to revert to the old XML format from Java SE 8 and before. See the java.util.logging.XMLFormatter API documentation for more details.

There could also be an issue if a subclass of LogRecord overrides getMillis/setMillis without calling the implementation of the super class. In that case, the event time as seen by the formatters and other classes may be wrong, as these have been updated to no longer call getMillis() but use getInstant() instead.

See JDK-8072645
 java.util.logging.FormatterformatMessage API specification has been clarified, and its implementation fixed.

java.util.logging.Formatter.formatMessage API specification specified that MessageFormat would be called if the message string contained "{0". In practice MessageFormat was called if the message string contained either "{0", "{1", "{2" or "{3".

In Java SE 9, the specification and implementation of this method have been changed to call MessageFormat if the message string contains "{<digit>", where <digit> is in [0..9].

In practice, this should be transparent for calling applications.

The only case where an application might see a behaviour change is if the application passes a format string that does not contain any formatter of the form "{0", "{1", "{2" or "{3", but contains "{<digit>" with <digit> within [4..9], along with an array of parameters that contains at least <digit>+1 elements, and depends on MessageFormat not to be called. In that case the method will return a formatted message instead of the format string.

See JDK-8153666
 Loggers with handlers configured from the logging.properties configuration file will not be garbage collected until LogManager.reset is called.

When a logger has a handler configured in the logging configuration file (using the <logger>.handlers property), a reference to that logger will be internally kept by the LogManager until LogManager.reset() is called, in order to ensure that the associated handlers are properly closed on reset. As a consequence, such loggers won't be garbage collected until LogManager.reset() is called. An application that needs to allow garbage collection of these loggers before reset is called can revert to the old behaviour by additionally specifying <logger>.handlers.ensureCloseOnReset=false in the logging configuration file. Note however that doing so will reintroduce the resource leak that JDK-8060132 is fixing. Such an application must therefore take the responsibility of keeping the logger alive as long as it is needed, and close any handler attached to it before the logger gets garbage collected. See LogManager API documentation for more details.

See JDK-8060132
 A new configurable property in logging.properties java.util.logging.FileHandler.maxLocks

A new "java.util.logging.FileHandler.maxLocks" configurable property is added to java.util.logging.FileHandler.

This new logging property can be defined in the logging configuration file and makes it possible to configure the maximum number of concurrent log file locks a FileHandler can handle. The default value is 100.

In a highly concurrent environment where multiple (more than 101) standalone client applications are using the JDK Logging API with FileHandler simultaneously, it may happen that the default limit of 100 is reached, resulting in a failure to acquire FileHandler file locks and causing an IO Exception to be thrown. In such a case, the new logging property can be used to increase the maximum number of locks before deploying the application.

If not overridden, the default value of maxLocks (100) remains unchanged. See java.util.logging.LogManager and java.util.logging.FileHandler API documentation for more details.

See JDK-8153955
 LogManager.readConfiguration will no longer propagate IllegalArgumentException directly when the logging configuration property file contains invalid unicode escape sequences.

LogManager.readConfiguration calls Properties.load, which may throw IllegalArgumentException if it encounters an invalid unicode escape sequence in the input stream. In previous versions of the JDK, the IllegalArgumentException was simply propagated to the caller. This was however in violation of the specification, since LogManager.readConfiguration is not specified to throw IllegalArgumentException. Instead, it is specified to throw IOException ''if there are problems reading from the stream''. In Java SE 9, LogManager.readConfiguration will no longer propagate such IllegalArgumentException directly, but will wrap it inside an IOException in order to conform to the specification.

See JDK-8075810
 Align behavior and spec for java.util.regex.Pattern.compile()

Pattern.compile(String, int) will throw IllegalArgumentException if anything other than a combination of predefined values is passed as the second argument, in accordance with the specification.

See JDK-8035975
 Arrays.asList().toArray() returns Object[]

The Arrays.asList() API returns an instance of List. Calling the toArray() method on that List instance is specified always to return Object[], that is, an array of Object. In previous releases, it would sometimes return an array of some subtype. Note that the declared return type of Collection.toArray() is Object[], which permits an instance of an array of a subtype to be returned. The specification wording, however, clearly requires an array of Object to be returned.

The toArray() method has been changed to conform to the specification, and it now always returns Object[]. This may cause code that was expecting the old behavior to fail with a ClassCastException. An example of code that worked in previous releases but that now fails is the following:

    List<String> list = Arrays.asList("a", "b", "c");
    String[] array = (String[]) list.toArray();

If this problem occurs, rewrite the code to use the one-arg form toArray(T[]), and provide an instance of the desired array type. This will also eliminate the need for a cast.

    String[] array = list.toArray(new String[0]);
See JDK-6260652
 List.spliterator should optimize for RandomAccess lists

Previously the default implementation of List.spliterator derived a Spliterator from the List's iterator, which is poorly splitting and that affects the performance of a parallel stream returned by List.parallelStream. The default implementation of List.spliterator now returns an optimal splitting Spliterator implementation for List implementations that implement java.util.RandomAccess. As a result parallel stream performance may be improved for third-party List implementations, such as those provided by Eclipse collections, that do not override List.spliterator for compatibility across multiple major versions of the Java platform. This enhancement is a trade-off. It requires that the List.get method, of such lists implementing RandomAccess, have no side-effects, ensuring safe concurrent execution of the method when parallel stream pipeline is executed.

See JDK-8158365
 Collections.asLifoQueue(null) now throws NPE as specified

Before the JDK 9 release, invocation of the method Collections.asLifoQueue with a null argument value would not throw a NullPointerException as specified by the class documentation. Instead a NullPointerException would be thrown when operating on the returned Queue. The JDK 9 release corrects the implementation of Collections.asLifoQueue to conform to the specification. Behavioral compatibility is not preserved but it is expected that the impact will be minimal given analysis of existing usages.

See JDK-8145006
 SPI based locale sensitive services need to be explicitly specified

The default locale data provider lookup does not load SPI based locale sensitive services. If it is needed, the system property "java.locale.providers" needs to designate "SPI" explicitly. For more detail, refer to LocaleServiceProvider.

See JDK-8138613
 Provide a better migration path for ResourceBundleControlProvider

In releases through JDK 8, SPI implementations of java.util.spi.ResourceBundleControlProvider were loaded using Java Extension Mechanism. In JDK 9, this mechanism is no longer available. Instead, SPI implementations may be placed on an application's class path.

See JDK-8172365
 Locale sensitive SPI and Input Method SPI implementations are now loaded from application's classpath

Prior to JDK 9, SPI implementations of java.awt.im.spi, java.text.spi, and java.util.spi packages used the Java Extension Mechanism. In JDK 9, this mechanism has been removed. SPI implementations should now be deployed on the application class path or as module on the module path.

See JDK-8062588
 JDK 9 supports CLDR version 29

The locale data based on the Unicode Consortium's CLDR (Common Locale Data Registry) has been upgraded in JDK 9 to release release 29. See http://cldr.unicode.org/index/downloads/cldr-29 for more detail.

See JDK-8145136
 Exported elements referring to inaccessible types in java.naming

The javax.naming.CompoundName, an extensible type, has a protected member, impl whose type, javax.naming.NameImpl, is package-private. This is a long standing issue where an inaccessible implementation type has mistakenly made its way into the public Java SE API.

The new javac lint option javac -Xlint helped identify this issue. In Java SE 9, this protected member has been removed from the public API.


Since the type of the member is package-private it cannot be directly referenced by non-JDK code. The member type does not implement or extend any super type directly, therefore any non-JDK subtype of javax.naming.CompoundName could only refer to this member as Object. It is possible that such a subtype might invoke the toString, or any of Object's methods on this member, or even synchronize on it. In such a case such subtypes of javax.naming.CompoundName will require updating.

Source incompatible:

Code making a static reference to the member will fail to compile, e.g. error: impl has private access in CompoundName

Binary incompatible:

Previously compiled code executed with JDK 9, accessing the member directly will fail, e.g. java.lang.IllegalAccessError: tried to access field javax.naming.CompoundName.impl from class CompoundName$MyCompoundName

See JDK-8167178
 JDWP socket connector accept only local connections by default

The JDWP socket connector has been changed to bind to localhost only if no ip address or hostname is specified on the agent command line. A hostname of asterisk (*) may be used to achieve the old behavior which is to bind the JDWP socket connector to all available interfaces; this is not secure and not recommended.

JDK-8041435 (not public)
 Agent JAR added to app class loader rather than system class loader when running with -Djava.system.class.loader

When running a java application with the options "-javaagent:myagent.jar -Djava.system.classloader=MyClassLoader", myagent.jar is added to the custom system class loader rather than the application class loader.

In addition, the java.lang.instrument package description has a small update making it clear that a custom system class loader needs to define appendToClassPathForInstrumentation in order to load the agent at startup. Before custom system class loaders were required to implement this method only if the agents are started in the live phase (Agent_OnAttach).

See JDK-8160950
 Changes in logging interface in MXBean

In Java SE 9 the java.util.logging.LoggingMXBean interface is deprecated in favor of the java.lang.management.PlatformLoggingMXBean interface. The java.util.logging.LogManager.getLoggingMXBean() method is also deprecated in favor of java.lang.mangement.ManagementFactory.getPlatformMXBean(PlatformLoggingMXBean.class).

The concrete implementation of the logging MXBean registered in the MBeanServer and obtained from the ManagementFactory will only implement java.lang.management.PlatformLoggingMXBean, and no longer java.util.logging.LoggingMXBean. It must be noted that PlatformLoggingMXBean and LoggingMXBean attributes are exactly the same. The PlatformLoggingMXBean interface has all the methods defined in LoggingMXBean, and so PlatformLoggingMXBean by itself provides the full management capability of logging facility.

This should be mostly transparent to remote and local clients of the API.


Calls to ManagementFactory.newPlatformMXBeanProxy(MBeanServerConnection, ObjectName, java.util.logging.LoggingMXBean.class) and calls to JMX.newMXBeanProxy(MBeanServerConnection, ObjectName, java.util.logging.LoggingMXBean.class) will continue to work as before.

Remote clients running any version of the JDK should see no changes, except for the interface name in MBeanInfo, and the change in isInstanceOf reported in 1. and 2. below.

The behavioral change and source incompatibility due to this change are as follows:

  1. ManagementFactory.getPlatformMBeanServer().isInstanceOf(ObjectName, "java.util.logging.LoggingMXBean") will now return 'false' instead of 'true'.

    If an application depends on this, then a workaround is to change the source of the calling code to check for java.lang.management.PlatformLoggingMXBean instead.

  2. The Logging MXBean MBeanInfo will now report that its management interface is java.lang.management.PlatformLoggingMXBean instead of the non standard sun.management.ManagementFactoryHelper$LoggingMXBean name it used to display.

    The new behavior has the advantage that the reported interface name is now a standard class.

  3. Local clients which obtain an instance of the logging MXBean by calling ManagementFactory.getPlatformMXBean(PlatformLoggingMXBean.class) will no longer be able to cast the result to java.util.logging.LoggingMXBean.

    PlatformLoggingMXBean already has all the methods defined in LoggingMXBean, therefore a simple workaround is to change the code to accept PlatformLoggingMXBean instead - or change it to use the deprecated LogManager.getLoggingMXBean() instead.

See JDK-8139982
 JMX Diagnostic improvements

com.sun.management.HotSpotDiagnostic::dumpHeap API is modified to throw IllegalArgumentException if the supplied file name does not end with “.hprof” suffix. Existing applications which do not provide a file name ending with the “.hprof” extension will fail with IllegalArgumentException. In that case, applications can either choose to handle the exception or restore old behaviour by setting system property 'jdk.management.heapdump.allowAnyFileSuffix' to true.

JDK-8176055 (not public)
 JMX ObjectName optimized to reduce memory footprint

JMX ObjectName class is refactored and 8 bytes of class member metadata was reduced.

Each instance size of JMX ObjectName in memory is 8 bytes less than JDK8 ObjectName instance.

A new restriction on domain name length is introduced. The domain name now is a case sensitive string of limited length. The domain name length limit is Integer.MAX_VALUE/4.

JDK-8041565 (not public)
 Define ConstructorParameters annotation type for MXBeans

A new annotation @javax.management.ConstructorParameters in the java.management module is introduced.

The newly introduced annotation will be 1:1 copy of @java.beans.ConstructorProperties. Constructors annotated by @java.beans.ConstructorProperties will still be recognized and processed.

In case a constructor is annotated by both @javax.management.ConstructorParameters and @java.beans.ConstructorProperties only the @javax.management.ConstructorParameters will be used.

See JDK-8139727
 Attach API cannot be used to attach to the current VM by default

The implementation of Attach API has changed in JDK 9 to disallow attaching to the current VM by default. This change should have no impact on tools that use the Attach API to attach to a running VM. It may impact libraries that mis-use this API as a way to get at the java.lang.instrument API. The system property jdk.attach.allowAttachSelf may be set on the command line to mitigate any compatibility with this change.

See JDK-8178380
 Parsing of <param> elements in JavaFX application JNLP

JavaFX applications deployed with

<application-desc type="JavaFX"> <param name="param1" value="foo"/> </application-desc>

will have their <param> elements ignored. It is recommended that JavaFX applications relying on parameter values continue to use the <javafx-desc> element of the xml extension until this is resolved.

See JDK-8182495
 JNLP files won't launch from IE11 on Windows 10 Creators Update

Web-start applications cannot be launched when clicking JNLP link from IE 11 on Windows 10 Creators Update when 64-bit JRE is installed. Workaround is to uninstall 64-bit JRE and use only 32-bit JRE.

See JDK-8185661
 JnlpDownloadServlet no longer available

JDK 9 no longer contains samples, including the JnlpDownloadServlet. If you need to use the JnlpDownloadServlet, you can get it from the latest update of JDK 8.

JDK-8174956 (not public)
 Support of Deployment Technologies

Starting with JDK 9, support for deployment technologies designed to access Java Applications through a web browser is limited to client and development platforms. Use of deployment technologies on server platforms such as Oracle Linux, Suse Linux, Windows Server 2016, and others is not supported. See the (link to complete list)JDK 9 and JRE 9 Certified System Configurations(link) page for a complete list.

JDK-8134633 (not public)
 Deployment Tookit API methods no longer installs JRE

The Deployment Toolkit API installLatestJRE() and installJRE(requestedVersion) methods from deployJava.js and install() method from dtjava.js no longer installs the JRE. If a user's version of Java is below the security baseline, it redirects the user to java.com to get an updated JRE.

JDK-8148310 (not public)
 -srcdir Option in Java Packager cmdline not functioning as documented

Documentation for the Java Packager states that the -srcfiles argument is not mandatory, and if omitted all files in the directory specified by the -srcdir argument will be used. This is not functioning as expected. When -srcfiles is omitted, the resultant bundle may issue a class not found error.

See JDK-8151377
 For Java Web Start, custom XML parser replaced with SAX parser

In 8u20, the custom XML parser that was used in Java Web Start to parse jnlp file was replaced with the standard SAX parser. When a parsing error occurred, the code would print a warning message to the Java Console and Trace file, and then try again using the custom XML parser. In JDK 9 this fallback has been removed. If the jnlp file cannot be parsed by the SAX parser an error dialog will show and the app will not run. This could cause compatibility errors with existing JNLP files that don't follow the XML rules that are enforced by the SAX parser.

JDK-8064476 (not public)
 URLStreamHandlerFactory unavailable to Web Start applications

In JDK 9, Java Web Start applications are prohibited from using URLStreamHandlerFactory. Using URLStreamHandlerFactory via javaws will result in an exception with the message "factory already defined."

Applications launched directly with java command are not impacted.

See JDK-8178799
 Web Start and Plug-in support of VM arguments with embedded spaces

New-style JVM arguments, those with embedded spaces (e.g., "--add-modules <module>" and "--add-exports <module>" instead of, "--add-modules=<module>" and "--add-exports=<module>") will not be supported when passed through Java Web Start or Plug-in. If arguments with embedded spaces are passed, they could be processed incorrectly.

See JDK-8166438
 AVX-512 (AVX3) instructions set support

JDK 9 will support code generation for AVX-512 (AVX3) instructions set on x86 CPUs, but not by default. A maximum of AVX2 is supported by default in JDK 9. The flag -XX:UseAVX=3 can be used to enable AVX-512 code generation on CPUs that support it.

See JDK-8184036
 Interpreter and compiled code process signaling NaN values inconsistently in 32-bit x86 VM

The IEEE 754 standard distinguishes between signaling and quiet NaNs. When executing floating point operations, some processors silently convert signaling NaNs to quiet NaNs. The 32-bit x86 version of the HotSpot JVM allows silent conversions to happen. With JVM releases preceding JDK 9, silent conversions happen depending on whether the floating point operations are part of compiled or interpreted code. With the JDK 9 release, interpreted and compiled code behaves consistently with respect to signaling and quiet NaNs.

See JDK-8076373
 Compilers accept modification of final fields outside initializer methods

According to the Java VM Specification, final fields can be modified by the putfield byte code instruction only if the instruction appears in the instance initializer method <init> of the field's declaring class. Similar, static final fields can be modified by a putstatic instruction only if the instruction appears in the class initializer method <clinit> of the field's declaring class. With the JDK 9 release, the HotSpot VM fully enforces the previously mentioned restrictions, but only for class files with version number >= 53. For class files with version numbers < 53, restrictions are only partially enforced (as it is done by releases preceding JDK 9). That is, for class files with version number < 53 final fields can be modified in any method of the class declaring the field (not only class/instance initializers).

See JDK-8157181
 Emulate client build on platforms with reduced virtual address space

The 32-bit Client VM was removed from linux-x86 and Windows. As a result, the -client flag is ignored with 32-bit versions of Java on this platform. The 32-bit Server VM is used instead. However, due to limited virtual address space on Windows in 32-bit mode, by default the Server VM emulates the behavior of the Client VM and only uses the C1 JIT compiler, Serial GC, 32Mb CodeCache. To revert to server mode, the flag -XX:{+|-}TieredCompilation can be used. On linux-x86 there is no Client VM mode emulation.

See JDK-8166002
 Use Unified Logging for GC logging

The logging for all garbage collectors in HotSpot have been changed to make use of a new logging framework that is configured through the -Xlog command line option. The command line flags -XX:+PrintGC, -XX:+PrintGCDetails and -Xloggc have been deprecated and will likely be removed in a future release. They are currently mapped to similar -Xlog configurations. All other flags that were used to control garbage collection logging have been removed. See the documentation for -Xlog for details on how to now configure and control the logging. These are the flags that were removed:

CMSDumpAtPromotionFailure, CMSPrintEdenSurvivorChunks, G1LogLevel, G1PrintHeapRegions, G1PrintRegionLivenessInfo, G1SummarizeConcMark, G1SummarizeRSetStats, G1TraceConcRefinement, G1TraceEagerReclaimHumongousObjects, G1TraceStringSymbolTableScrubbing, GCLogFileSize, NumberOfGCLogFiles, PrintAdaptiveSizePolicy, PrintClassHistogramAfterFullGC, PrintClassHistogramBeforeFullGC, PrintCMSInitiationStatistics, PrintCMSStatistics, PrintFLSCensus, PrintFLSStatistics, PrintGCApplicationConcurrentTime, PrintGCApplicationStoppedTime, PrintGCCause, PrintGCDateStamps, PrintGCID, PrintGCTaskTimeStamps, PrintGCTimeStamps, PrintHeapAtGC, PrintHeapAtGCExtended, PrintJNIGCStalls, PrintOldPLAB, PrintParallelOldGCPhaseTimes, PrintPLAB, PrintPromotionFailure, PrintReferenceGC, PrintStringDeduplicationStatistics, PrintTaskqueue, PrintTenuringDistribution, PrintTerminationStats, PrintTLAB, TraceDynamicGCThreads, TraceMetadataHumongousAllocation, UseGCLogFileRotation, VerifySilently

See JDK-8145092
 Enforce format checks for NameAndType strings

This change enforces the unqualified name format checks for NameAndType strings as outlined in the JVM specification sections 4.4.6 and 4.2.2, meaning that some illegal names and descriptors that users may be utilizing in their classfiles will now be caught with a Class Format Error. This includes format checking for all strings under non-referenced NameAndType's. Users will see a change if they (A) are using Java classfile version 6 or below and have an illegal NameAndType descriptor with no Methodref or Fieldref reference to it; or (B) are using any Java classfile version and have an illegal NameAndType name with no Methodref or Fieldref reference to it.

In both (A) and (B) the users will now receive a ClassFormatError for those illegal strings, which is an enforcement of unqualified name formats as delineated in JVMS 4.2.2.

See JDK-8161224
 Stack overflow can cause segfaults on Linux

Some linux kernel versions (including, but not limited to 3.13.0-121-generic and 4.4.0-81-generic) are known to contain an incorrect fix for a linux kernel stack overflow issue (See CVE-2017-1000364). The incorrect fix can trigger crashes in the Java Virtual Machine. Upgrading the kernel to a version that includes the corrected fix addresses the problem.

See JDK-8182777
 Additional consistency checks for JVM_CONSTANT_Methodref and JVM_CONSTANT_InterfaceMethodref

The JVM has been fixed to check that the constant pool types JVM_CONSTANT_Methodref or JVM_CONSTANT_InterfaceMethodref are consistent with the type of method referenced. These checks are made during method resolution and are also checked for methods that are referenced by JVM_CONSTANT_MethodHandle.

If consistency checks fail an IncompatibleClassChangeError is thrown.

javac has never generated inconsistent constant pool entries, but some bytecode generating software may. In many cases, if ASM is embedded in the application, upgrading to the latest version ASM 5.1 resolves the exception. After upgrading ASM, be sure to replace all uses of deprecated functions with calls to the new functions, particularly new functions that pass a boolean whether the method is an interface method: visitMethodInsn and Handle.

See JDK-8145148
 Update JNI Version Number

The current version of the Java Native Interface (JNI) needs to be updated due to the addition of new application programmatic interfaces to support Jigsaw. JNI_VERSION_9 was added with a value of 0x00090000 to the available versions and CurrentVersion was changed to this new value.

See JDK-8145098
 VM Options AdaptiveSizePausePolicy and ParallelGCRetainPLAB are obsolete

The VM Options -XX:AdaptiveSizePausePolicy and -XX:ParallelGCRetainPLAB are obsolete in JDK 9 and are ignored. Use of these options will result in a warning being issued in JDK 9 and they may be removed completely in a future release.

The VM Option -XX:AdaptiveSizePausePolicy has been unused for some time.

The VM Option -XX:ParallelGCRetainPLAB was a diagnostic flag relating to garbage collector combinations that no longer exist.

See JDK-8073861
 JNIDetachReleasesMonitors is obsolete

The -XX:-JNIDetachReleasesMonitors flag requested that the VM run in a pre-JDK 6 compatibility mode with regard to not releasing monitors when a JNI attached thread detaches. This option is obsolete in JDK 9, and is ignored, as the VM always conforms to the JNI Specification and releases monitors. Use of this option will result in a warning being issued in JDK 9 and it may be removed completely in a future release.

See JDK-8131045
 VM Options "-Xoss", "-Xsqnopause", "-Xoptimize" and "-Xboundthreads" are obsolete

The VM Options "-Xoss", "-Xsqnopause", "-Xoptimize" and "-Xboundthreads" are obsolete in JDK 9 and are ignored. Use of these options will result in a warning being issued in JDK 9 and they may be removed completely in a future release.

The VM Options "-Xoss", "-Xsqnopause", "-Xoptimize" options were already silently ignored for a long time.

The VM Option "-Xboundthreads" was only needed on Solaris 8/9 (when using the T1 threading library).

See JDK-8078399
 The JNI function DetachCurrentThread must tolerate pending exceptions

The JNI function DetachCurrentThread has been added to the list of JNI functions that can safely be called with an exception pending. The HotSpot Virtual Machine has always supported this as it reports that the exception occurred in a similar manner to the default handling of uncaught exceptions at the Java level. Other implementations are not obligated to do anything with the pending exception.

See JDK-8155881
 Windows 32 no longer offers client JVM

JDK 8 and below offered a client JVM and a server JVM for Windows 32-bit systems with the default being the client JVM. JDK 9 will offer only the server JVM.

The server JVM has better performance although it might require more resources. The change is made to reduce complexity and to benefit from the increased capabilities of computers.

JDK-8134633 (not public)
 Binary format for HPROF updated

When dumping the heap in binary format, HPROF format 1.0.2 is always used now. Previously, format 1.0.1 was used for heaps smaller than 2GB. HPROF format 1.0.2 is also used by jhsdb jmap for the serviceability agent.

See JDK-8144732
 'jsadebugd' command has been replaced by 'jhsdb debugd' command.

The jsadebugd command to start remote debug server can now be launched from the common SA launcher jhsdb .

The new command to start remote debug server is jhsdb debugd .

See JDK-8160817
 Support system or alternative implementations of zlib

The Java runtime now uses system zlib library (the zlib library installed on the underlying operation system) for its zlib compression support (the deflation and inflation functionality in java.util.zip, for example) on Solaris and Linux platforms.

See JDK-8031767
 OS_VERSION property in `release` file removed

OS_VERSION property is no longer present in the release file. Scripts or tools that read the release file may need to be updated to handle this change.

See JDK-8175819
 Restrictions when running the installer on Windows under the user LocalSystem

The REMOVEOUTOFDATEJRES feature does not work when the install is run via LocalSystem user. LocalSystem user is not a domain user, therefore it does not have network access to get the list of out of date jre's.

See JDK-8157556
 Stage background is now filled with Scene fill color

Starting with the JDK 9 release, a Stage on Mac and Linux platforms will be initially filled using the Fill property of the Scene if its Fill is a Color. An average color, computed within the stops range, will be used if the Fill is a LinearGradient or RadialGradient. Previously, it was initially filled with WHITE, irrespective of the Fill in the Scene. This change in behavior will reduce the flashing that can be seen with a dark Scene background, but applications should be aware of this change in behavior so they can set an appropriate Fill color for their Scene.

See JDK-8088179
 A singleton ORB configured via the system property must be visible to the system class loader

If the singleton ORB is configured with the system property org.omg.CORBA.ORBSingletonClass or the equivalent key in orb.properties then the class must be visible to the system class loader. Previous releases incorrectly attempted to load the class using the Thread Context Class Loader (TCCL). An @implNote has been added to org.omg.CORBA.ORB to document the behavior.

The change does not impact the loading of ORB implementations configured with the system property org.omg.CORBA.ORBClass or the equivalent key in orb.properties. The ORB implementation configured with this property is loaded using the TCCL to allow for applications that bundle an ORB implementation with the application.

JDK-8031154 (not public)
 orb.idl and ir.idl moved to include directory

orb.idl and ir.idl have moved from the JDK lib directory to the include directory. Applications that use a CORBA IDL compiler in their build may need to change the include path from $JAVA_HOME/lib to $JAVA_HOME/include.

See JDK-8049389
 Extend the search path for the org.omg.CORBA.ORB orb.properties file

org.omg.CORBA.ORB specifies the search order to locate an ORB's orb.properties file, and this includes searching ${java.home}/lib. The JDK 9 release will include a ${java.home}/conf directory as the location for properties files. As such, the ORB.init processing has been amended, to include ${java.home}/conf directory in its search path for an orb.properties file. Thus, the preferred approach is to use the ${java.home}/conf directory, in preference to the ${java.home}/lib directory, as a location for an orb.properties file.

See JDK-8049376
 More checks added to DER encoding parsing code

More checks are added to the DER encoding parsing code to catch various encoding errors. In addition, signatures which contain constructed indefinite length encoding will now lead to IOException during parsing. Note that signatures generated using JDK default providers are not affected by this change.

JDK-8168714 (not public)
 Message digest algorithms are now enabled by default for SunPKCS11 provider on Solaris

SunPKCS11 provider has re-enabled support for various message digest algorithms such as MD5, SHA1, and SHA2 on Solaris. If you are using Solaris 10 and experience a CloneNotSupportedException or PKCS11 error CKR_SAVED_STATE_INVALID, you should verify and apply the below patches or newer version of them: 150531-02 on sparc 150636-01 on x86

See JDK-8037745
 De-privileged module permissions granted by default

When using a SecurityManager, the permissions required by JDK modules are granted by default, and are not dependent on the policy.url properties that are set in the java.security file.

This also applies if you are setting the java.security.policy system property with either the '=' or '==' option.

See JDK-8159752
 Custom Policy Providers may need additional configuration

Classes loaded from the extensions directory are no longer granted AllPermission by default. See JDK-8040059.

A custom java.security.Policy provider that was using the extensions mechanism may be depending on the policy grant statement that had previously granted it AllPermission. If the policy provider does anything that requires a permission check, the local policy file may need to be adjusted to grant those permissions.

Also, custom policy providers are loaded by the system class loader. The classpath may need to be configured to allow the provider to be located.

See JDK-8075706
 keytool now prints warnings when reading or generating certificates/certificate requests/CRLs using weak algorithms

With one exception, keytool will always print a warning if the certificate, certificate request, or CRL it is parsing, verifying, or generating is using a weak algorithm or key. When a certificate is from an existing TrustedCertificateEntry, either in the keystore directly operated on or in the cacerts keystore when the -trustcacerts option is specified for the -importcert command, keytool will not print a warning if it is signed with a weak signature algorithm. For example, suppose the file cert contains a CA certificate signed with a weak signature algorithm, keytool -printcert -file cert and keytool -importcert -file cert -alias ca -keystore ks will print out a warning, but after the last command imports it into the keystore, keytool -list -alias ca -keystore ks will not show a warning anymore.

Precisely, an algorithm or a key is weak if it matches the value of the jdk.certpath.disabledAlgorithms security property defined in the conf/security/java.security file.

See JDK-8171319
 Update SecurityManagercheckPackageAccess to restrict non-exported JDK packages by default

The implementation of the checkPackageAccess and checkPackageDefinition methods of java.lang.SecurityManager now automatically restrict all non-exported packages of JDK modules loaded by the platform class loader or its ancestors. This is in addition to any packages listed in the package.access and package.definition security properties. A "non-exported package" refers to a package that is not exported to all modules. Specifically, it refers to a package that either is not exported at all by its containing module or is exported in a qualified fashion by its containing module.

If your application is running with a SecurityManager, it will need to be granted an appropriate accessClassInPackage.{package} RuntimePermission to access any internal JDK APIs (in addition to specifying an appropriate --add-exports option). If the application has not been granted access, a SecurityException will be thrown.

Note that an upgraded JDK module may have a different set of internal packages than the corresponding system module, and therefore may require a different set of permissions.

The package.access and package.definition properties no longer contain internal JDK packages that are not exported. Therefore, if an application calls Security.getProperty("package.access"), it will not include the builtin non-exported JDK packages.

Also, when running under a SecurityManager, an attempt to access a type in a restricted package that does not contain any classes now throws a ClassNotFoundException instead of an AccessControlException. For example, loading sun.Foo now throws a ClassNotFoundException instead of an AccessControlException because there are no classes in the sun package.

See JDK-8055206
 Restrict certificates with DSA keys less than 1024 bits.

DSA keys less than 1024 bits are not strong enough and should be restricted in certification path building and validation. Accordingly, DSA keys less than 1024 bits have been deactivated by default by adding "DSA keySize < 1024" to the "jdk.certpath.disabledAlgorithms" security property. Applications can update this restriction in the security property ("jdk.certpath.disabledAlgorithms") and permit smaller key sizes if really needed (for example, "DSA keySize < 768").

JDK-8139565 (not public)
 Required Algorithms for JDK 9

The following have been added to the security algorithm requirements for JDK implementations (keysize in parentheses):

  1. Signature: SHA256withDSA
  2. KeyPairGenerator: DSA (2048), DiffieHellman (2048, 4096), RSA (4096)
  3. AlgorithmParameterGenerator: DSA (2048), DiffieHellman (2048)
  4. Cipher: AES/GCM/NoPadding (128), AES/GCM/PKCS5Padding (128)
  5. SSLContext: TLSv1.1, TLSv1.2
  6. TrustManagerFactory: PKIX
See JDK-8015388
 Add MD5 to jdk.certpath.disabledAlgorithms security property

In this update, MD5 is added to the jdk.certpath.disabledAlgorithms security property and the use of the MD5 hash algorithm in certification path processing is restricted in the Oracle JRE. Applications using certificates signed with a MD5 hash algorithm should upgrade their certificates as soon as possible.

Note that this is a behavior change of the Oracle JRE. It is not guaranteed that the security property (jdk.certpath.disabledAlgorithms) is examined and used by other JRE implementations.

JDK-8030829 (not public)
 jarsigner treats timestamped signed jar invalid after the signer cert expires

If a jar file was signed with a timestamp when the signer certificate was still valid, it should be valid even after the signer certificate expires. However, jarsigner will incorrectly show a warning that that signer's certificate chain is not validated. This will be fixed in a future release.

See JDK-8180289
 Support added to jarsigner for specifying timestamp hash algorithm

A new -tsadigestalg option is added to jarsigner to specify the message digest algorithm that is used to generate the message imprint to be sent to the TSA server. In older JDK releases, the message digest algorithm used was SHA-1. If this new option is not specified, SHA-256 will be used on JDK 7 Updates and later JDK family versions. On JDK 6 Updates, SHA-1 will remain the default but a warning will be printed to the standard output stream.

See JDK-8038837
 Security providers are now loaded through ServiceLoader and registered by name

As part of work for JEP 220 "Modular Run-Time Images", security providers loading mechanism is enhanced to support modular providers through java.util.ServiceLoader. The default JDK security providers have been refactored to be modular providers and registered inside java.security file by provider name instead of provider class name. As for providers which have not been re-worked to modules, they should be registered by provider class names in java.security file.

See JDK-7191662
 keytool now prints out information of a certificate's public key

Keytool now prints out the key algorithm and key size of a certificate's public key, in the form of "Subject Public Key Algorithm: <size>-bit RSA key", where <size> is the key size in bits (ex: 2048).

See JDK-8029659
 Change in SecureRandom Thread Safety

SecureRandom objects are safe for use by multiple concurrent threads. A SecureRandom service provider can advertise that it is thread-safe by setting the service provider attribute "ThreadSafe" to "true" when registering the provider. Otherwise, the SecureRandom class will synchronize access to the following SecureRandomSpi methods: SecureRandomSpi.engineSetSeed(byte[]), SecureRandomSpi.engineNextBytes(byte[]), SecureRandomSpi.engineNextBytes(byte[], SecureRandomParameters), SecureRandomSpi.engineGenerateSeed(int), and SecureRandomSpi.engineReseed(SecureRandomParameters).

See JDK-7004967
 jarsigner -verbose -verify should print the algorithms used to sign the jar

The jarsigner tool has been enhanced to show details of the algorithms and keys used to generate a signed JAR file and will also provide an indication if any of them are considered weak.

Specifically, when "jarsigner -verify -verbose filename.jar" is called, a separate section is printed out showing information of the signature and timestamp (if it exists) inside the signed JAR file, even if it is treated as unsigned for various reasons. If any algorithm or key used is considered weak, as specified in the Security property jdk.jar.disabledAlgorithms, it will be labeled with "(weak)".

For example:

- Signed by "CN=weak_signer"
    Digest algorithm: MD2 (weak)
    Signature algorithm: MD2withRSA (weak), 512-bit key (weak)
  Timestamped by "CN=strong_tsa" on Mon Sep 26 08:59:39 CST 2016
    Timestamp digest algorithm: SHA-256
    Timestamp signature algorithm: SHA256withRSA, 2048-bit key
See JDK-8163304
 Disallow null values for Subject inputs

Inputs to the javax.security.auth.Subject class now prohibit null values in the constructors and modification operations on the Principal and credential Set objects returned by Subject methods.

For the non-default constructor, the principals, pubCredentials, and privCredentials parameters may not be null, nor may any element within the Sets be null. A NullPointerException will be thrown if null values are provided.

For operations performed on Set objects returned by getPrincipals(), getPrivateCredentials() and getPublicCredentials(), a NullPointerException is thrown under the following conditions:

See JDK-8015081
 New default -sigalg and -keysize for jarsigner and keytool

Default signature algorithms for jarsigner and keytool are determined by both the algorithm and the key size of the private key which makes use of comparable strengths as defined in Tables 2 and 3 of NIST SP 800-57 Part 1-Rev.4. Specifically, for a DSA or RSA key with a key size greater than 7680 bits, or an EC key with a key size greater than or equal to 512 bits, SHA-512 will be used as the hash function for the signature algorithm. For a DSA or RSA key with a key size greater than 3072 bits, or an EC key with a key size greater than or equal to 384 bits, SHA-384 will be used. Otherwise, SHA-256 will be used. The value may change in the future.

For DSA keys, the default key size for keytool has changed from 1024 bits to 2048 bits.

There are a few potential compatibility risks associated with these changes:

  1. If you use jarsigner to sign JARs with the new defaults, previous versions (than this release) might not support the stronger defaults and will not be able to verify the JAR. jarsigner -verify on such a release will output the following error:

    jar is unsigned. (signatures missing or not parsable)

    If you add -J-Djava.security.debug=jar to the jarsigner command line, the cause will be output:

    jar: processEntry caught: java.security.NoSuchAlgorithmException: SHA256withDSA Signature not available

    If compatibility with earlier releases is important, you can, at your own risk, use the -sigalg option of jarsigner and specify the weaker SHA1withDSA algorithm.

  2. If you use a PKCS11 keystore, the SunPKCS11 provider may not support the SHA256withDSA algorithm. jarsigner and some keytool commands may fail with the following exception if PKCS11 is specified with the -storetype option, ex:

    keytool error: java.security.InvalidKeyException: No installed provider supports this key: sun.security.pkcs11.P11Key$P11PrivateKey

    A similar error may occur if you are using NSS with the SunPKCS11 provider. The workaround is to use the -sigalg option of keytool and specify SHA1withDSA.

  3. If you have a script that uses the default key size of keytool to generate a DSA keypair but then subsequently specifies a specific signature algorithm, ex:

    keytool -genkeypair -keyalg DSA -keystore keystore -alias mykey ...
    keytool -certreq -sigalg SHA1withDSA -keystore keystore -alias mykey ...

    it will fail with one of the following exceptions, because the new 2048-bit keysize default is too strong for SHA1withDSA:

    keytool error: java.security.InvalidKeyException: The security strength of SHA-1 digest algorithm is not sufficient for this key size
    keytool error: java.security.InvalidKeyException: DSA key must be at most 1024 bits

    You will see a similar error if you use jarsigner to sign JARs using the new 2048-bit DSA key with -sigalg SHA1withDSA set.

    The workaround is to remove the -sigalg option and use the stronger SHA256withDSA default or, at your own risk, use the -keysize option of keytool to create new keys of a smaller key size (1024).

See JDK-8057810, JDK-8056174 and JDK-8138766 for more details.

See JDK-8138766
 DomainCombiner will no longer consult runtime policy for static ProtectionDomain objects when combining ProtectionDomain objects.

Applications which use static ProtectionDomain objects (created using the 2-arg constructor) with an insufficient set of permissions may now get an AccessControlException with this fix. They should either replace the static ProtectionDomain objects with dynamic ones (using the 4-arg constructor) whose permission set will be expanded by the current Policy or construct the static ProtectionDomain object with all the necessary permissions.

JDK-8147771 (not public)
 Fix denyAfter and usage types for security properties

A new constraint named 'usage' has been added to the 'jdk.certpath.disabledAlgorithms' security property, that when set, restricts the algorithm if it is used in a certificate chain for the specified usage(s). Three usages are initially supported: 'TLSServer' for restricting authentication of TLS server certificate chains, 'TLSClient' for restricting authentication of TLS client certificate chains, and 'SignedJAR' for restricting certificate chains used with signed JARs. This should be used when disabling an algorithm for all usages is not practical. The usage type follows the keyword and more than one usage type can be specified with a whitespace delimiter. For example, to disable SHA1 for TLS server and client certificate chains, add the following to the property: "SHA1 usage TLSServer TLSClient"

The 'denyAfter' constraint has been added to the 'jdk.jar.disabledAlgorithms' security property. When set, it restricts the specified algorithm if it is used in a signed JAR after the specified date, as follows:

a. if the JAR is not timestamped, it will be restricted (treated as unsigned) after the specified date

b. if the JAR is timestamped, it will not be restricted if it is timestamped before the specified date.

For example, to restrict usage of SHA1 in jar files signed after January 1, 2018, add the following to the property: "SHA1 denyAfter 2018-01-01".

See JDK-8160655
 Change in the default keystore type to PKCS12

As of JDK 9, the default keystore type (format) is "pkcs12" which is based on the RSA PKCS12 Personal Information Exchange Syntax Standard. Previously, the default keystore type was "jks" which is a proprietary format. Other keystore formats are available, such as "jceks" which is an alternate proprietary keystore format with stronger encryption than "jks" and "pkcs11", which is based on the RSA PKCS11 Standard and supports access to cryptographic tokens such as hardware security modules and smartcards.

See JDK-8044445
 DSA signature generation is now subject to a key strength check

For signature generation, if the security strength of the digest algorithm is weaker than the security strength of the key used to sign the signature (e.g. using (2048, 256)-bit DSA keys with SHA1withDSA signature), the operation will fail with the error message: "The security strength of SHA1 digest algorithm is not sufficient for this key size."

JDK-8138593 (not public)
 Default key sizes for the AlgorithmParameterGenerator and KeyPairGenerator implementations updated

To improve security, the default key size for the RSA and DiffieHellman KeyPairGenerator implementations and the DiffieHellman AlgorithmParameterGenerator implementations has been increased from 1024 bits to 2048 bits. The default key size for the DSA KeyPairGenerator and AlgorithmParameterGenerator implementations remains at 1024 bits to preserve compatibility with applications that are using keys of that size with the SHA1withDSA signature algorithm.

With increases in computing power and advances in cryptography, the minimum recommended key size increases over time. Therefore, future versions of the platform may increase the default size.

See JDK-8138653
 Updated Java Cryptography Jurisdiction Policy File Mechanism

This release introduces several changes to the JCE Jurisdiction Policy files.

Previously, to allow unlimited cryptography in the JDK, separate JCE Jurisdiction Policy files had be be downloaded and installed. The download and install steps are no longer necessary.

  1. Both the strong but "limited" (traditional default) and the "unlimited" policy files are included in this release.

  2. A new Security property (crypto.policy) was introduced to control which policy files are active. The new default is "unlimited".

  3. The files are now user-editable to allow for customized Policy configuration.

Please see the Java Cryptography Architecture (JCA) Reference Guide for more information.

Also see:

JDK-8186093: java.security configuration file still says that "strong but limited" is the default value

See JDK-8061842
 Improve the default strength of EC in JDK.

To improve the default strength of EC cryptography, EC keys less than 224 bits have been deactivated in certification path processing (via the "jdk.certpath.disabledAlgorithms" Security Property) and SSL/TLS/DTLS connections (via the "jdk.tls.disabledAlgorithms" Security Property) in JDK. Applications can update this restriction in the Security Properties and permit smaller key sizes if really needed (for example, "EC keySize < 192").

EC curves less than 256 bits are removed from the SSL/TLS/DTLS implementation in JDK. The new System Property, "jdk.tls.namedGroups", defines a list of enabled named curves for EC cipher suites in order of preference. If an application needs to customize the default enabled EC curves or the curves preference, please update the System Property accordingly. For example:

jdk.tls.namedGroups="secp256r1, secp384r1, secp521r1"

Note that the default enabled or customized EC curves follow the algorithm constraints. For example, the customized EC curves cannot re-activate the disabled EC keys defined by the Java Security Properties.

See JDK-8148516
 Increase the priorities of GCM cipher suites

In TLS, a ciphersuite defines a specific set of cryptography algorithms used in a TLS connection. JSSE maintains a prioritized list of ciphersuites. In this update, GCM-based cipher suites are configured as the most preferable default cipher suites in the SunJSSE provider.

In the SunJSSE provider, the following ciphersuites are now the most preferred by default:




Note that this is a behavior change of the SunJSSE provider in the JDK, it is not guaranteed to be examined and used by other JSSE providers. There is no guarantee the cipher suites priorities will remain the same in future updates or releases.

See JDK-8028518
 Modify requirements on Authority Key Identifier extension field during X509 certificate chain building

The requirement to have the Authority Key Identifier (AKID) and Subject Key Identifier (SKID) fields matching when building X509 certificate chains has been modified for some cases.

See JDK-8072463
 Disable MD5withRSA signature algorithm in the JSSE provider

The MD5withRSA signature algorithm is now considered insecure and should no longer be used. Accordingly, MD5withRSA has been deactivated by default in the Oracle JSSE implementation by adding "MD5withRSA" to the "jdk.tls.disabledAlgorithms" security property. Now, both TLS handshake messages and X.509 certificates signed with MD5withRSA algorithm are no longer acceptable by default. This change extends the previous MD5-based certificate restriction ("jdk.certpath.disabledAlgorithms") to also include handshake messages in TLS version 1.2. If required, this algorithm can be reactivated by removing "MD5withRSA" from the "jdk.tls.disabledAlgorithms" security property.

JDK-8144773 (not public)
 Restrict Diffie-Hellman keys less than 1024 bits

Diffie-Hellman keys less than 1024 bits are considered too weak to use in practice and should be restricted by default in SSL/TLS/DTLS connections. Accordingly, Diffie-Hellman keys less than 1024 bits have been disabled by default by adding "DH keySize < 1024" to the "jdk.tls.disabledAlgorithms" security property in the java.security file. Although it is not recommended, administrators can update the security property ("jdk.tls.disabledAlgorithms") and permit smaller key sizes (for example, by setting "DH keySize < 768").

JDK-8148108 (not public)
 auth.login.LoginContext needs to be updated to work with modules

After this change, besides implementing the necessary methods (initialize, login, logout, commit, abort), any login module must implement the LoginModule interface. Otherwise a LoginException will be thrown when the login module is used.

See JDK-8047789
 Increase the minimum key length to 1024 for XML Signatures

The secure validation mode of the XML Signature implementation has been enhanced to restrict RSA and DSA keys less than 1024 bits by default as they are no longer secure enough for digital signatures. Additionally, a new security property named jdk.xml.dsig.SecureValidationPolicy has been added to the java.security file and can be used to control the different restrictions enforced when the secure validation mode is enabled.

The secure validation mode is enabled either by setting the xml signature property org.jcp.xml.dsig.secureValidation to true with the javax.xml.crypto.XMLCryptoContext.setProperty method, or by running the code with a SecurityManager.

If an XML Signature is generated or validated with a weak RSA or DSA key, an XMLSignatureException will be thrown with the message "RSA keys less than 1024 bits are forbidden when secure validation is enabled" or "DSA keys less than 1024 bits are forbidden when secure validation is enabled".

JDK-8140353 (not public)
 The XML Digital Signature API (javax.xml.crypto and subpackages) has been enhanced to better support generics

The XML Digital Signature APIs (the javax.xml.crypto package and subpackages) have been enhanced to better support Generics, as follows:

See JDK-8046949
 rcache interop with krb5-1.15

The hash algorithm used in the Kerberos 5 replay cache file (rcache) is updated from MD5 to SHA256 with this change. This is also the algorithm used by MIT krb5-1.15. This change is interoperable with earlier releases of MIT krb5, which means Kerberos 5 acceptors from JDK 9 and MIT krb5-1.14 can share the same rcache file.

A new system property named jdk.krb5.rcache.useMD5 is introduced. If the system property is set to "true", JDK 9 will still use the MD5 hash algorithm in rcache. This is useful when both of the following conditions are true: 1) the system has a very coarse clock and has to depend on hash values in replay attack detection, and 2) interoperability with earlier versions of JDK for rcache files is required. The default value of this system property is "false".

See JDK-8168518
 Support the "s" (second) unit for kdc_timeout in krb5.conf

An interoperability issue is found between Java and the native Kerberos implementation on BSD (including macOS) on the kdc_timeout setting in krb5.conf, where Java interpreted it as milliseconds and BSD as seconds when no unit is specified. This code change adds support for the "s" (second) unit. Therefore if the timeout is 5 seconds, Java accepts both "5000" and "5s". Customers concerned about interoperability between Java and BSD should use "5s".

See JDK-8036779
 implement eager resolution of return types

The compiler specification, see JLS8 18.5.2, modified the treatment of nested generic method invocations for which the return type is an inference variable. The compiler has been adapted to implement the new logic. This is important to minimize incompatibility with the javac 7 inference algorithm. Three cases are considered:

The compiler update implies an eager resolution for generic method invocations, provided that the return type is an inference variable.

See JDK-8030741
 Javac incorrectly allows receiver parameters in annotation methods

javac was erroneously accepting receiver parameters in annotations methods. This implies that tests cases like the one below were being accepted:

@interface MethodRun {
    int value(MethodRun this);

The JLS 8, see JLS8 9.6.1, doesn't allow any formal parameter in annotation methods, this extends to receiver parameters. More specifically, the grammar for annotation types does not allow arbitrary method declarations, instead allowing only AnnotationTypeElementDeclarations. The allowed syntax is:

{AnnotationTypeElementModifier} UnannType Identifier ( ) [Dims] [DefaultValue];

Note that nothing is allowed between the parentheses.

See JDK-8175198
 Changes in the way javac handles wildcards and capture type variables

The javac compiler's behavior when handling wildcards and "capture" type variables has been improved for conformance to the language specification. This improves type checking behavior in certain unusual circumstances. It is also a source-incompatible change: certain uses of wildcards that have compiled in the past may fail to compile because of a program's reliance on the javac bug.

See JDK-8039214
 Several incorporation steps are silently failing when an error should be reported

Reporting previously silent errors found during incorporation, JLS 8 §18.3, was supposed to be a clean-up with performance only implications. But consider the test case:

import java.util.Arrays;
import java.util.List;

class Klass {
    public static <A> List<List<A>> foo(List<? extends A>... lists) {
        return foo(Arrays.asList(lists));

    public static <B> List<List<B>> foo(List<? extends List<? extends B>> lists) {
        return null;

This code was not accepted before the patch for [1], but after this patch the compiler is accepting it. Accepting this code is the right behavior as not reporting incorporation errors was a bug in the compiler.

While determining the applicability of method:

<B> List<List<B>> foo(List<? extends List<? extends B>> lists)

For which we have the constraints:

b <: Object
t <: List<? extends B>
t<: Object
List<? extends A> <: t

First, inference variable b is selected for instantiation:

b = CAP1 of ? extends A

so this implies that:

t <: List<? extends CAP1 of ? extends A>
t<: Object
List<? extends A> <: t

Now all the bounds are checked for consistency. While checking if List<? extends A> is a subtype of List<? extends CAP1 of ? extends A> a bound error is reported. Before the compiler was just swallowing it. As now the error is reported while inference variable b is being instantiated, the bound set is rolled back to it's initial state, 'b' is instantiated to Object, and with this instantiation the constraint set is solvable, the method is applicable, it's the only applicable one and the code is accepted as correct. The compiler behavior in this case is defined at JLS 8 §18.4

This fix has source compatibility impact, right now code that wasn't being accepted is now being accepted by the javac compiler. Currently there are no reports of any other kind of incompatibility.

[1] [https://bugs.openjdk.java.net/browse/JDK-8078024](https://bugs.openjdk.java.net/browse/JDK-8078024)

See JDK-8078024
 Missing error in qualified default super call

Javac was not in sync with JLS 8 §15.12.1, specifically:

If the form is TypeName . super . [TypeArguments] Identifier, then: ...

Let T be the type declaration immediately enclosing the method invocation. It is a compile-time error if I is not a direct superinterface of T, or if there exists some other direct superclass or direct superinterface of T, J, such that J is a subtype of I.

So javac was not issuing a compiler error for cases like:

interface I {
    default int f(){return 0;}

class J implements I {}

class T extends J implements I {
    public int f() {
        return I.super.f();

The compiler had some checks for method invocations of the form:

TypeName . super . [TypeArguments] Identifier

but there was one issue. If TypeName is an interface I and T is the type declaration immediately enclosing the method invocation, the compiler must issue a compile-time error if there exists some other direct superclass or superinterface of T, let's call it J such that J is a subtype of I, as in the example above.

See JDK-8058244
 Missing unchecked warnings when checking method reference return types

javac does not generate unchecked warnings when checking method reference return types.

import java.util.function.*;
import java.util.*;

class Test {
   void m() {
      IntFunction<List<String>[]> sls = List[]::new; //warning
      Supplier<List<String>> sls = this::l; //warning

   List l() { return null; }

Starting from 9, javac will emit a warning when unchecked conversion is required for a method reference to be compatible with a functional interface target.

This change brings the compiler in sync with JLS section 15.13.2:

A compile-time unchecked warning occurs if unchecked conversion was necessary for the compile-time declaration to be applicable, and this conversion would cause an unchecked warning in an invocation context.


A compile-time unchecked warning occurs if unchecked conversion was necessary for the return type R', described above, to be compatible with the function type's return type, R, and this conversion would cause an unchecked warning in an assignment context.

See JDK-8175317
 Add compile-time check for invalid or out-of-range ConstantValue attributes

The classfile format (see JVMS section 4.7.2) defines an attribute called ConstantValue which is used to describe the constant value associated with a given (constant) field. The layout of this attribute is as follows:

ConstantValue_attribute {
    u2 attribute_name_index;
    u4 attribute_length;
    u2 constantvalue_index;

Historically, javac has never performed any kind of range validation of the value contained in the constant pool entry at constantvalue_index. As such, it is possible for a constant field of type e.g. boolean to have a constant value other than 0 or 1 (the only legal values allowed for a boolean). Starting from 9, javac will start detecting ill-formed ConstantValue attributes, and report errors if out-of-range values are found.

See JDK-8171132
 javac creates output directories as needed.

Output directories required by javac, specified with the -d, -s, -h options, will be created if they do not already exist.

See JDK-8143268
 Support for @-files in javac, javadoc, javah aligned with launcher support

The support for "argument files" on the command lines for javac, javadoc, and javah, has been updated to better align with the support for argument files on the launcher command line. This includes the following two new features:

  1. Quotes may be used within a word as well as surrounding a word, to enclose special characters like white space and escape sequences
  2. Long lines may be split across lines by using the escape sequence "\" "newline" "whitespace"

Some obscure, undocumented escape sequences are no longer supported. The files are still read using the default platform file encoding, whereas argument files on the launcher command line should use ASCII or an ASCII-compatible encoding, such as UTF-8.

See JDK-8162810
 javac no longer marks anonymous classes 'static'

Prior to JDK 9, javac set the 'static' modifier on anonymous classes declared in a static context, e.g., in static methods or static initialization blocks. This contradicts the Java Language Specification, which states that anonymous classes are never static. In JDK 9, javac does not mark anonymous classes 'static', whether they are declared in a static context or not.

See JDK-8034044
 javadoc may exit on non-compliant sources.

If any errors are encountered while reading or analyzing the source code, the javadoc tool will treat them as unrecoverable errors and exit.

See JDK-8175219
 Compact javadoc display of single-element annotations

Previously javadoc would include "value=" when displaying annotations even when that text was not necessary in the source because the annotations were of single-element annotation type (JLS 9.6. Annotation Type Elements ). The extraneous "value=" text is now omitted, leading to more concise annotation display.

See JDK-6469562
 Omit public and abstract modifiers in javadoc for annotation type members

Previously javadoc would emit "public" and "abstract" modifiers for methods and fields in annotation types. These flags are not needed in source code and are elided for non-annotation interface types. With this change, those modifiers are also omitted for methods and fields defined in annotation types.

See JDK-6469561
 File URI is not a valid class path element

The class path specified to the java launcher is expected to be a sequence of file paths. Previous releases incorrectly accept a Windows path with a leading slash, for example, -classpath /C:/classes, is not the intended behavior. The implementation of the application class loader has been changed in JDK 9 to use the new file system API which detects that /C:/classes is not a valid file path. Existing application specifying file URI on the class path will need to change and specify a valid file path.

See JDK-8185596
 The launcher no longer uses ergonomics to select the VM

In previous releases, on platforms that supported more than one VM, the launcher could use ergonomics to select the Server VM over the Client VM. Ergonomics would identify a "server-class" machine based on the number of CPUs and the amount of memory. With modern hardware platforms most machines are identified as server-class, and so now, only the Server VM is provided on most platforms. Consequently the ergonomic selection is redundant and has been removed. Users are advised to use the appropriate launcher VM selection flag on those systems where multiple VMs still exist.

See JDK-8169001
 XMLInputFactory.newFactory incorrectly deprecated

The @Deprecated annotation was incorrectly added to the newFactory() method in javax.xml.stream.XMLInputFactory. The method should not be deprecated. The newInstance() method can be used to avoid the deprecation warning. A future release will correct this.

See JDK-8183519
 XSLT stylesheets with erroneously placed import elements are now rejected

In accordance with XSL Transformations (XSLT) Version 1.0 (http://www.w3.org/TR/xslt), the xsl:import element is only allowed as a top-level element. The xsl:import element children must precede all other element children of an xsl:stylesheet element, including any xsl:include element children.

The JDK implementation has previously allowed the xsl:import element erroneously placed anywhere in a stylesheet. This issue has been fixed in the JDK 9 release. The JDK implementation now rejects any XSLT stylesheets with erroneously placed import elements.

See JDK-8058152
 JAX-WS, JAXB, JAF are deprivileged and defined by platform class loader

The defining class loader of java.xml.ws, java.xml.bind, and java.activation module and their classes is changed to the platform class loader (non-null) (see the specification for java.lang.ClassLoader::getPlatformClassLoader).

Existing code that assumes the defining class loader of JAX-WS, JAXB, JAF classes may be impacted by this change (e.g. custom class loader delegation to the bootstrap class loader skipping the extension class loader).

See JDK-8057645
 JAXB does not open packages with inner types of JAXB annotated classes

JAXBContext specifies that classes annotated with @XmlRootType should be specified at context creation time to JAXBContext.newInstance(Class[] classesToBeBound, ...)

If the client classes are in a named module, than openness of the packages containing these classes is not propagated correctly when the root JAXB classes reference JAXB types in another package.

For example, given the following Java classes:

@XmlRootElement2 class Foo { Bar b;} @XmlType class Bar { FooBar fb;} @XmlType class FooBar { int x; }

The invocation of JAXBContext.newInstance(Foo.class) registers Foo and the statically referenced classes, Bar and FooBar.

If Bar and FooBar are in different package than Foo, than openness is not propagated for them with current implementation.

The issue can be worked around by opening the package with the opens directive in the module declaration. Alternatively, the --add-opens command line option can be used to open the package:

For example: --add-opens foo.mymodule/bar.baz=ALL-UNNAMED (for JAXB-RI on classpath) --add-opens foo.mymodule/bar.baz=<jaxb-impl> (for JABX implementations on the application module path)

See JDK-8185721
 JAXP library updated with selected Xerces 2.11.0 updates

The JAXP library in JDK 9 has been updated to Xerces-J 2.11.0 release in the following areas:

This update includes improvement and bug fixes in the above areas up to the Xerces-J 2.11.0 release, but not the experimental support for XML Schema 1.1 features. Refer to Xerces-J 2.11.0 Release Notes for more details.

See JDK-8044086
 Non Java SE DOM APIs moved to jdk.xml.dom module

Before the Java SE 9 release, the DOM API package in org.w3c.dom included sub-packages that were not defined as a part of the Jave SE API. As of Java SE 9, these sub-packages are moved out of the java.xml module to a separate module called jdk.xml.dom. These packages are as follows:

See JDK-8042244
 Revamping the pretty print feature for Transformer and LSSerializer

The JAXP library through the Transformer and LSSerializer supports a pretty print feature that can format the output by adding whitespaces and newlines to produce a more readable form of an XML document. As of the JDK 9 release, this feature has been enhanced to generate a format similar to that of the major web browsers. In addition, the xml:space attribute as defined in the XML specification (https://www.w3.org/TR/2006/REC-xml-20060816/#sec-white-space) is now supported.

The Pretty-Print feature does not define the actual format. The output format can change over time or vary from implementation to implementation, and therefore should not be relied on for exact text comparison. It is recommended that such applications turn off the Pretty-Print feature and perform an XML to XML comparison.

See JDK-8087303
 OOME caused by very large CDATA section in XML document can now be avoided

An event-based XML parsers may return character data in chunks.

SAX specification: states that SAX parsers may return all contiguous character data in a single chunk, or they may split it into several chunks.

StAX specification: did not specify explicitly.

The JDK implementation before JDK 9 returns all character data in a CData section in a single chunk by default. As of JDK 9, an implementation-only property jdk.xml.cdataChunkSize is added to instruct a parser to return the data in a CData section in a single chunk when the property is zero or unspecified, or in multiple chunks when it is greater than zero. The parser will split the data by linebreaks, and any chunks that are larger than the specified size to ones that are equal to or smaller than the size.

The property jdk.xml.cdataChunkSize is supported through the following means:

  1. through the SAX or StAX API, that is SAXParser or XMLReader for SAX, and XMLInputFactory for StAX. If the property is set, its value will be used in preference over any of the other settings.
  2. as a system property. The value set in the system property will overwrite that in jaxp.properties, but may be overridden by the API setting above.
  3. in the jaxp.properties file. The value in jaxp.properties may be overridden by the system property or an API setting.
See JDK-8158619