Hi TingTing. I'm not sure what you're question is so I don't know how to help you.
So zhapool what are the assumptions you can make about your program? I'm guessing these some upper limit to the number you want to convert? Cause really it would be a mission to translate every possible number! Or maybe I just don't see the obvious way to do it.
I think you'll be using the switch statement and some carefully placed if statements. The trick is the algorithm. Let's have a look at how you think it's solved and we will help you tweak it and make it into Java :)