Library for building Android Apps.
Contains high-level classes encapsulating the overall Android application model.
Contains classes for accessing application resources, such as raw asset files, colors, drawables, media, or other files in the package, plus important device configuration details (orientation, input types, etc.) that affect how the application may behave.
Contains components used when developing applications with data binding.
Provides low level graphics tools such as canvases, color filters, points, and rectangles that let you handle drawing to the screen directly.
Internationalization.
Dependency injection.
Provides for system input and output through data streams, serialization and the file system.
Manages your activity and fragment lifecycles.
Provides basic operating system services, message passing, and inter-process communication on the device.
Provides classes used to render or track text and text spans on the screen.
Provides data types.
Provides classes that expose basic user interface classes that handle screen layout and interaction with the user.
The widget package contains (mostly visual) UI elements to use on your Application screen.