Migrate to Java Platform, Standard Edition 8
This product version supports the Java Platform, Standard Edition (Java SE) 8 specification. Its Java virtual machine provides a Java language compiler and runtime environment. Decide whether the new and existing applications will take advantage of the capabilities added by Java SE 8, and begin the transition from deprecated functions.
Java SE 8 includes new features such as Lambda expression support and virtual extension methods, a more understandable date and time API, and improved security. Java SE 8 offers support for WebSphere applications to use the latest available Java features and standards. For more information about new Java features, see What's new in Java 8 on the Oracle website.
Support for Java SE 8 is provided by the IBM SDK, v8. For information about what is new in IBM SDK, v8, see IBM SDK, v8.
Tasks
- Decide whether to take advantage of new Java SE 8 capabilities in the applications.
We can deploy applications using Java SE 8 features only to v9.0 or v8.5.5.9 or later nodes, as earlier product versions do not provide the Java SE 8 virtual machine.
- Compile Java SE 8 applications that do not use new capabilities to run on previous Java virtual machine levels by setting the compiler modes.
When compiling applications that are built with Java SE 8 intended for running on previous specifications, specify -source and -target modes for the Java SE 8 compiler. Doing so ensures that the bytecode generated is compatible with the earlier Java virtual machine.
For example, if the target Java virtual machine is at 1.6 level, when you compile applications with Java SE 8, we should specify -source 1.6, and -target 1.6 to generate bytecode compatible with 1.6. This does not handle the usage of packages, classes, or functions new to Java SE 8. It only addresses bytecode output. Developers must take care in what APIs they are using from the Java SE packages if they intend to run the application on multiple Java virtual machine specification levels.
- Address incompatibilities in previously compiled Java SE applications.
Java SE 8 is upwards binary-compatible with previous Java SE versions, except for the incompatibilities and deprecations that are documented in the Oracle Compatibility Guide for JDK 8.
Rather than manually looking through the applications for API and specification changes, scan the applications for any required changes using the Migration Toolkit for Application Binaries and the WAS Migration Toolkit.
The application binary scanner provides a detailed migration analysis report for the application, so we can better understand the type and scope of changes that the application might require. When we migrate the applications, the Eclipse-based migration toolkit provides quick fixes to automatically update our source when possible and provides detailed help for items that must be manually updated.
For more information and to download the toolkit, see the Migration Toolkit on WASdev.
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Related:
Java SE 8 in WAS traditional V9 Java virtual machine settings Java SE Java SE compatibility