basic java

[shanmuk surya]

Hi to all,
my doubt is whether the java virtual machine is available in the operating system or as part of the jdk kit.
It is said that the jvm is system dependent and the .class files are system independent.
for ex:I have two pcs ,where linux runs on one machine and windows on another machine.I have a jdk1.5 kit to install on both of the systems.so does the same jdk1.5 kit works for both the operating systems or i should get some other jdk.

[Ulf Dittmer]

The JVM is part of the JDK or the JRE, but it may come preinstalled with your operating system. If it is, you have either the JDK or the JRE as well. Confusing, isn't it?

The bottom line is, if you know that you have a JDK installed on both machines, you are set to run Java.

[Jesper de Jong]

The JVM (Java Virtual Machine) is the engine.
The JRE (Java Runtime Environment) is the complete car, including the engine.

The JDK (Java Development Kit) includes the JRE (and JVM) and a bunch of tools that you need when you want to write your own Java programs.

Class files compiled with the Windows JDK run on the JRE on any operating system, you don't need to recompile them. So yes, you can compile your Java source code on Windows and run the class files on Linux (provided you're using the correct JDK/JRE versions).

There is a specific JDK and JRE for each operating system. You cannot use the JDK and JRE for Windows on Linux.

[Adam Richards]

Another way to explain it:

The JVM is *not* part of the operating system (OS). Its OS independence comes from the fact that JVM's have been written for many different OS's. All you have to do is install the one for *your* OS.