JDK vs JRE vs J2SE vs J2EE vs J2ME ?

Which Java should I download? Can I just download the minimum small file size Java? Well, it depend on what are you need it for. Below explains;

JDK = Java Development Kit
Contains all of the software needed to compile Java source files (.java) into bytecode (.class)

JRE = Java Runtime Environment
Software needed to run the bytecode.

The JRE does come with the JDK. So, if you just want to run Java program, downloading JRE will do. The JRE installer is about 15MB while the JDK installer is about 55MB.

Quick introduction about Java? Read here.

J2SE = Java 2 Standard Edition
JDK + JRE, Java development package.

J2EE = Java 2 Enterprise Edition
JDK + JRE, advance Java development package.

J2ME = Java 2 Micro Edition
JDK + JRE, for handheld devices (cellular phones, palmtops etc.)

Quick way to know your Java version? Type java –version on your dos or shell prompt.

Java version example on WinXP command prompt



Java version example on Solaris 10 shell through PuTTY



More Java version checking methods can be found here