We release the "Swingdroid" project into open source today.
Swingdroid lets you port a Java Android app to Windows/Mac desktop as a Java swing application.
Swingdroid does not require an emulator, and does not require you change any code. Swingdroid provides an implementation of the Android class library that uses Java swing components. This enables Android app to runs as native Java swing apps.
Swingdroid is available from Github here,