JDK 22 Early-Access Release Notes

The park, unpark, getLoadAverage, loadFence, storeFence, and fullFence methods defined by sun.misc.Unsafe have been deprecated for removal.

Code using these methods should move to java.util.concurrent.LockSupport.park/unpark (Java 5), java.lang.management.OperatingSystemMXBean.getSystemLoadAverage (Java 6), and java.lang.invoke.VarHandle.xxxFence (Java 9).

A new property jdk.xml.dtd.support is introduced that determines how XML processors handle DTDs. The new property can be set on factory APIs, as a Java system property, or in the JAXP Configuration File. The new property affects all XML processors uniformly.

The new property complements the two existing DTD properties: disallow-doctype-decl (fully qualified name: http://apache.org/xml/features/disallow-doctype-decl), which is applicable only to the DOM and SAX processors, and supportDTD (javax.xml.stream.supportDTD), which is applicable only to the StAX processor. When one of these existing properties is set on the respective processor factory, its value will take precedence over any value specified for the jdk.xml.dtd.support property.

For further information, see the Configuration section of the java.xml module summary.

The following root certificate has been added to the cacerts truststore:

+ Certigna (Dhimyotis)
  + certignarootca
    DN: CN=Certigna Root CA, OU=0002 48146308100036, O=Dhimyotis, C=FR

The -XshowSettings:all and -XshowSettings launch options now differ in behavior. -XshowSettings will print a summary view for the locale and security categories and all information for the other categories. -XshowSettings:all will continue to print all settings information available.

The -XshowSettings launcher option will now reject bad values passed to it. In such cases, an error message is printed and the JVM launch is aborted. See java -X for valid options that can be used with the -XshowSettings option.

The system property, jdk.jar.maxSignatureFileSize, allows applications to control the maximum size of signature files in a signed JAR. Its default value has been increased from 8000000 bytes (8 MB) to 16000000 bytes (16 MB).

In previous releases MethodHandleProxies::asInterfaceInstance returns a Proxy instance. MethodHandleProxies::asInterfaceInstance has been reimplemented to return instances of a hidden class that can be unloaded when all instances returned for the same interface becomes unreachable. Once unloaded, subsequent call to MethodHandleProxies::asInterfaceInstance will spin and define a new hidden class that may incur performance overhead.

System.console() has changed in this release to return a Console with enhanced editing features that improve the experience of programs that use the Console API. In addition, System.console() now returns a Console object when the standard streams are redirected or connected to a virtual terminal. In prior releases, System.console() returned null for these cases. This change may impact code that uses the return from System.console() to test if the VM is connected to a terminal. If needed, running with -Djdk.console=java.base will restore older behavior where the console is only returned when it is connected to a terminal.

A new method Console.isTerminal() has been added to test if console is connected to a terminal.

The -XshowSettings launcher has a new security category. Settings from security properties, security providers and TLS related settings are displayed with this option. A security sub-category can be passed as an argument to the security category option. See the output from java -X:

   -XshowSettings:security
       show all security settings and continue
   -XshowSettings:security:*sub-category*
       show settings for the specified security sub-category and continue. Possible *sub-category* arguments for this option include:
       all: show all security settings and continue
       properties: show security properties and continue
       providers: show static security provider settings and continue
       tls: show TLS related security settings and continue

Third party security provider details will be reported if they are included in the application class path or module path and such providers are configured in the java.security file.

The showSettings launcher option no longer prints available locales information by default, when -XshowSettings is used. The -XshowSettings:locale option will continue to print all settings related to available locales.

The -Xnoagent option of the java command has been deprecated for removal. This option has been ignored for many releases and doesn't provide any functionality. It will now generate a deprecation warning when used while launching java:

OpenJDK 64-Bit Server VM warning: Option -Xnoagent was deprecated in JDK 22 and will likely be removed in a future release.

Any existing code which uses this option should be updated to remove reference to this option.

In the previous releases, MethodHandles.Lookup::findStaticVarHandle eagerly initializes the declaring class of the static field when the VarHandle is created. As specified in the specification, the declaring class should be initialized when the VarHandle is operated on if it has not already been initialized. This issue is fixed in this release. The declaring class is no longer eagerly initialized when MethodHandles.Lookup::findStaticVarHandle is called. Existing code that relies on the previous behavior may observe a change of the order of the classes being initialized.

Compact profiles became obsolete in Java SE 9 when modules were introduced. The jdeps -profile and -P options were deprecated for removal in JDK 21 and now removed in JDK 22. Customers can use jdeps to find the set of modules required by their applications instead.

The new core reflection implementation has been the default since JDK 18 and the old implementation is now removed. The -Djdk.reflect.useDirectMethodHandle=false introduced by JEP 416 to enable the old core reflection implementation becomes a no-op.

-XX:CompileCommand=... will now exit the VM with a non-zero exit code after a parsing error occurred.

-XX:CompileOnly=pattern1,[...],patternN is now an alias for -XX:CompileCommand=compileonly,pattern1 [...] -XX:CompileCommand=compileonly,patternN

The method java.lang.Thread.countStackFrames() has been removed in this release. This method dates from JDK 1.0 as an API for counting the stack frames of a suspended thread. The method was deprecated in JDK 1.2 (1998), deprecated for removal in Java 9, and re-specified/degraded in Java 14 to throw UnsupportedOperationException unconditionally.

java.lang.StackWalker was added in Java 9 as a modern API for walking the current thread's stack.

The shouldBeInitialized(Class) and ensureClassInitialized(Class) methods have been removed from sun.misc.Unsafe. These methods have been deprecated for removal since JDK 15. java.lang.invoke.MethodHandles.Lookup.ensureInitialized(Class) was added in Java 15 as a standard API to ensure that an accessible class is initialized.