How to implement Ceaser cipher encryption and decryption techniques using filesystem

[jalpesh_007]

I want a java program of ceaser cipher encryption and decryption technique.

in which you have to take input(plain text) from input.txt file and encrypt it with program and save the output(cipher text) in output.txt file.

again you have to take input from output(Cipher text) and apply decryption program and output(plain text) in output1.txt file..

SNIP

[NormR1]

I want a java program

Did you mean:
I want to write a java program ...

[stultuske]

firstly, what have you tried so far?

next: writing a class to perform the caesar shift is not that difficult, took me about 5 minutes couple of weeks ago.

my advice: write a class with the methods to perform the caesar shift, and use google (or your handbook, for that much) to find some info about how you read/write files.

try to write some code to do that, and if you run into problems, come back with your code, a list of errors/exceptions and specific questions, not a request to do your homework for you

[brandonrunyon]

Step 1: Gather together what the steps are that a computer needs to take to perform each requirement. Write it all out on paper, make sure you have it in depth. You need to make sure every step makes sense in context of every other step.

Step 2: Take those steps and match the 'noun' portions (files, filestream, parser, input, output, buffer, cipher, decipher...) and match them with objects that already exist or write your own accordingly.

Step 3: Then take the 'verb' words from your step-by-step you diligently wrote out and either find method members of your objects list or write your own that will perform the actions that will handle the information you put in, changes the clear text, and how it outputs.

Step 4: Combine your objects and your methods in ways that pass the information from input file --> filestream --> clear text to cipher methods --> file output stream --> encrypted file.

now that you know how to plan your software, you should try to locate and apply the main principles of the assignment.

1: File IO is a pretty integral part of programming and what you are doing, so it would benefit you to try some basic tutorials on it.
http://en.wikiversity.org/wiki/Java_File_IO

2: String manipulation is also a pretty important part of what you are doing, looking for chars and shifting them. I'd suggest looking at the whole string doc.
http://download.oracle.com/javase/1.5.0/docs/api/java/lang/String.html#toCharArray()

write some small practice programs that utilize these principles... you have to crawl before you can walk.