JDK Environment

 

JDK is Java Development Kit which is Physically exists.

It contains Development tools and JRE.

Development tools are nothing but small programs which are used for compilation, decompilation and preparing jar files etc.

Using JDK we can develop , compile and Execute the applications as well as we can modify already existing applications.

JRE :-

  JRE is Java Runtime environment , which provides only runtime environment i.e. it does not contain development tools

JRE contains JVM ,  set of libraries and other files that JVM uses at runtime.

Using JRE we can only execute already developed application.

JVM :-

 JVM stands for Java Virtual Machine , it is a java platform because it's responsible for executing  the java byte code by converting into machine code.

JVM internally contains Interpreter and JIT compiler which converts byte code into machine code.