I'm unable to delete data in a file in java.I tried to take whole data in to a string and manipulate it and output the data to the file.But it is stated in the problem that...it should not be done in that way.could anyone help me out??

The question has already been answered, so please take some time looking through some previous threads, or better yet use the search box at the top right of your screen. Also give us a complete description of your problem, give us some details as to what is your error, what is the compiler throwing up at you, and if your program is running what output are you getting and what you actually want, along with the code if possible.

Also I took the liberty to search for some old threads which have dealt with similar topics, here they are :-

http://www.daniweb.com/forums/thread164539.html
http://www.daniweb.com/forums/thread164619.html
http://www.daniweb.com/forums/thread164444.html
http://www.daniweb.com/forums/thread163689.html