Android to Unity3D migration?

I may already know the answer but I want to try anyway:
having coded and distrubuted native Java apps on Android at the time of Eclipse, is there a way (automatic or semi-automatic) to convert them and import them into Unity3D?
Of course they might need some work, so I don’t expect to push a button and see them inside the Unity Editor, but I wonder if there is at least some tool to make the migration possible without having to do everything by hand.
Thank you.

Whilst I’m certain you’ll be able to re-use most of your assets (images, sounds etc), actually porting the game to be ‘made with Unity’ will basically require you to re-write it. It uses a different language and you’ll need to take different things into consideration.

There are possibly some parts you can re-use by working them into Plugins, but that’s probably limited to system integration rather than any game play.