Searching for file extension in entire system

I have a created a tray application. User can tick t开发者_开发问答he file extensions which are available in the tray application to search. Therefore, when a user ticks a file extension, (letz assume .java) the tray application must search for all .java files in entire windows OS system.. i.e C:, D:, E:, etc. How could i do this ???

I think this is what you are looking for..

http://download.oracle.com/javase/tutorial/essential/io/find.html

A simple google search actually :)