Can someone help an old mainframe coder?

I'm looking for a basic java "hello world" type example that will:

1. display an input field
2. do something to the input (say multiply it by 2)
3. clear the screen
4. show the input and the result.

I'm totally new to OO code and the examples in the Sprint java developers kit have me bewildered. I'll have java books in a week or so, but I'd like to start playing...

TIA

Jeff Elkins
SCP8100