In loop Step We are giving input array And Output Array And Again We are mapping Why plase explain?
Any one is fine We need both? why?

Your questions are not making much sense so it is hard for others to respond helpfully.

Try searching the forums around your topic - arrays are often discussed and you may find some helpful hints out there already.

When posting, please give a context as to what you are trying to do, what you have attempted (perhaps include screen shots) and what results you are seeing that are different from what you are expecting. If you are getting an exception, include the actual error message.