Java Virtual Machine

     JVM is a virtual machine that act as an interpreter between java byte code and a computer’s operating system.By using JVM we can run java code on any platform.A JVM include a JIT(just-in-time)compiler within it.JIT compiler converts whole program to bytecodes . JVM recognizes a particular format of a file called “class file(extension.class)”. Each "class file(extension .class)" contains the definition of a single class or interface.



The compiler converts the source code files into byte code file. These byte codes are machine independent and therefore can be executed on any machine.Java interpreter translates the bytecode into binary codes . JVM is an interpreter for bytecode.


Source code   changeinto   Byte code --ByCompiler

Byte code       changeinto Real Machine Binary code--> By Java Interpreter


       Java environment includes a large number of development tools and hundreds of classes and methods.The development tools are parts of system known as JDK and the classes and methods are parts of the JSL,also known as API(Application program interface).


                   The JDK comes with the collection of tools that are used for developing and running java program.The tools are:

         a)appletviewer--------------to run java applets(view and test applets)

       b)Javac-------------------------Java compiler(compile java source code file into bytecodes)

       c)Java--------------------------Java Interpreter(used to execute java bytecodes)

       d)Javah------------------------For C header files.

       e)Javadoc----------------------For creating HTML document.


     JSL provides INPUT/OUTPUT ,String handling,networking and Graphics.