Android SDK vs. Play vs. webapp2

Android provides a rich application framework that allows you to build innovative apps and games for mobile devices in a Java language environment.

Play Framework makes it easy to build web applications with Java & Scala. Play is based on a lightweight, stateless, web-friendly architecture. Built on Akka, Play provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications.

webapp2 is a simple. it follows the simplicity of webapp, but improves it in some ways: it adds better URI routing and exception handling, a full featured response object and a more flexible dispatching mechanism.