Java Virtual Machine Overview

 

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The installable Java package supplied by IBM comes in two versions on Linux and Windows platforms:

Java Runtime Environment (JRE)	Runtime support
Java SDK	Includes JRE and well as Java compiler and other development tools.

The IBM SDK, V5.0 contains a different implementation of the JVM and the Just-In-Time compiler (JIT) from most earlier releases of the IBM SDK, apart from the v1.4.2 implementation on z/OS 64-bit and on AMD64/EM64T platforms.

To identify your version run...

java -version

Sample implementation output ...

5.0	IBM J9 VM (build 2.3, J2RE 1.5.0 IBM...
6	IBM J9 VM (build 2.4, J2RE 1.6.0 IBM...
1.4.2 'classic'	Classic VM (build 1.4.2, J2RE 1.4.2 IBM...
1.4.2 on z/OS 64-bit and AMD64/EM64T platforms	IBM J9SE VM (build 2.2, J2RE 1.4.2 IBM...
i5/OS 'classic' 1.3.1	java v"1.3.1" Java(TM) 2 Runtime Environment, Standard Edition (build ...) Classic VM (build 1.3, build JDK-1.3, native threads, jitc_de)
i5/OS 'classic' 1.4.2	java v"1.4.2" Java(TM) 2 Runtime Environment, Standard Edition (build ...) Classic VM (build 1.4, build JDK-1.4, native threads, jitc_de)
i5/OS 'classic' 1.5.0	java v"1.5.0" Java(TM) 2 Runtime Environment, Standard Edition (build ...) Classic VM (build 1.5, build JDK-1.5, native threads, jitc_de)
i5/OS 'classic' 1.6.0	java v"1.6.0" Java(TM) SE Runtime Environment (build ...) Classic VM (build 1.6, build JDK-1.6, native threads, jitc_de)