how to use messagedeigest class to bring security to a file...encode and decode a file...

any suggestion ?????

That's not what message digest does. Google java messagedigest tutorial to find out more.
Google java encryption decryption to find lots of tutorials and sample code

(Now, that wasn't hard was it? Next time maybe try Google first?)

ya am tried ...am not get any decryption(md5 hash) technique for decode and get a original value...here lot of professional there..they may know so only am posted here....

md5 hashes are NOT a method of encryption or decryption. That's why you can't find it. To encrypt/decrypt a file forget md5.
Google java encryption decryption to find lots of tutorials and sample code
When you get stuck come back here for help.

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