Running Your App. If you followed the previous lesson to create an Android project, it includes a default set of "Hello World" source files that allow you to immediately run the app.
How you run your app depends on two things: whether you have a real Android-powered device and whether you're using Eclipse. This lesson shows you how to install and run your app on a real device and on the Android emulator, and in both cases with either Eclipse or the command line tools. Before you run your app, you should be aware of a few directories and files in the Android project: AndroidManifest.xml. Android 4.0 Development Tutorial. Android Developers.