Hi!
If you use the standard android SDK (http://developer.android.com/sdk/index.html) all code is already done in JAVA and should already work in android. Just follow the instructions to set up eclipse and android sdk tools and then import your code to an android project.
The only thing that must be changed is the GUI (graphical user interface) since it's different in android. Do the "hello world" tutorial and "Hello, Views" tutorial in the android sdk page that should put you in the right track of how you should do GUI's in android ;)