•JDK-Java Development Kit
1.All development tools are in JDK.
For eg. Java, javac, javadoc, etc.
2.The main work is to compile and execute the java class.
3.It is mainly targeted for java development.
4.JDK=JRE+Development tools.
•JRE-Java Runtime Environment
1.It consist library classes(i.e.which is also mean of runtime environment) and JVM.
2.It doesn’t contain any development kit such as compiler, debugger, etc.
3.If you want to run any java program, you need to have JRE installed in system.
4.It provides the environment to run java program.
5.JRE=JVM+Library classes.
•JVM-Java Virtual Machine
1.It consist of class loader, memory area, execution engine.
2.It is a machine which convert and execute the bytecode in anywhere.
3.It is platform dependent, because configuration of each os differs and this makes java platform independent.
4.It forms following main tasks:
•Loads code.
•Verifies code.
•Executes code.
5.It runs the code line by line.