clarifications please...

[sridevi kumar]

1) diff between JVM and JRE:
JDK has JVM, JIT compiler, JFC, compiler, debugger, related tools and supporting files (libraries)
JRE has JVM, JIT compiler, JFC and supporting files
Is this correct?
2) what is JVM?
JVM executes your .class files (byte code which is platform independent) using java or javaw
is this correct?
3) diff between the exe files java and javaw?
a)
java executes non-gui program
javaw executes gui program
b)
javaw is identical to java but with one exception, there is no associated
console window with javaw...
When we use javaw, command prompt window won't appear.
However, if we are unable to launch for some reason, javaw will show a dialog box to display errors
c)
javaw is used when we want to run java application using icons (rather than in command window) in windows environment
(if this is true, then can't we use javaw in unix or in any other platform other than windows?)
please clarify whether my understanding is correct for questions 1 and 2
for question 3, please tell me which answer is correct... (whether a or b or c and also give definition for the exe files java and javaw)
Thanks a lot...

[amit mohanty]

There is a simple hierarchy.
JDK-JRE-JVM
In ur machine u can install JDK(Java developement Kit) or JRE(Java Runtime Environment).
When u install JDK it will install with JRE. U can istall simply the JRE without the JDK.
JRE contain the JVM.
JDK is the superset og JRE.
JDK used to develope with running the class file.
JRE used to simply run the programs.
JVM (Java Virtual Machine) is a exe file(in windows) which execute when u write java <class name>. It takes some system memory to execute.
Some more clarification, let me know.