Android Project StructureThe 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. Here’s a quick primer on the project structure, to help you make sense of it all, particularly for the sample code reference.
Android Build System Root ContentsWhen you create a new Android project (e.g., via android create project), you get several items in the project’s root directory, including the following:
AndroidManifest.xml : An XML file describing the application being built and which components, activities, services, and so on, are being supplied by that application.
build.xml : An Ant script for compiling the application and installing it on the device
default.properties and local.properties : Property files used by the Ant build script
assets/ : A folder that holds other static files you wish packaged with the application for deployment onto the device
bin : A folder that holds the application once it is compiled
gen/ : Where Android’s build tools will place source code that they generate
libs/ : A folder that holds any third-party JARs your application requires
src/ :A folder that holds the Java source code for the application
res/ : A folder that holds resources—such as icons, graphic user interface (GUI) layouts, and the like—that are packaged with the compiled Java in the application
tests/ :A folder that holds an entirely separate Android project used for testing the one you created