We present ProDroid, a framework that provides Android app developers an ability to quickly produce functional prototypes. With ProDroid, developers can create a new app that imports various kinds of functionality provided by other existing Android apps. Our evaluation shows that with the help of ProDroid, a developer was able to import a function from an existing Android app into a new prototype with only 55 lines of Java code, while the function itself requires 10,334 lines of Java code to implement.