The previous chapter stepped you through creating a stub project. This chapter describes what is inside of this project, so you understand what Android gives you at the outset and what the roles are for the various directories and files.
The Android build system is organized around a specific directory tree structure for your Android project, much like any other Java project. The specifics, though, are fairly unique to Android—the Android build tools do a few extra things to prepare the actual application that will run on the device or emulator. Here's a quick primer on the project structure, to help you make sense of it all, particularly for the sample code referenced in this book.