How to convert .Class file into .java (Decompiler)

This post discusses about how to convert a .class file into .java. In general we are unable to convert a .class file into .java programatically but it is not impossible we can do it by using a tool. If you are using eclipse then open Help in eclipse menu option then Install new softwares it will open a dialog box enter the following url into text area http://java.decompiler.free.fr/jd-eclipse/update     
then press next and finish. Eclipse asks u for restart the eclipse. After restart of the eclipse if u open any class file it will show you the source file of the .class.