Android API's

Android API's : Android provides a large number of specific libraries for applications development, in addition to many Java APIs. The following list of core Android APIs gives an insight into what will be surely supported by all Android devices:
Core APIs:
- Data structures

- File Structures

- Network Access

- Graphics

- Other Utilities

android.util: contains low-level classes like specialized containers, string formatters, and XML parsing utilities;

android.os: provides access to basic operating system services like message passing, inter process communication, clock functions, and debugging;

android.graphics supplies the low-level graphics classes;

android.text for displaying and parsing text;

android.database provides the low-level classes required for handling cursors when working with databases;

android.content is used to manage data access and publishing through services for dealing with resources, content providers, and packages;

android.view supplies classes for building the Graphic User Interface;

android.widget for drawing elements of the GUI's such as lists, buttons and layouts;

com.google.android.maps, a high-level API providing access to native map controls;

android.app, a high-level package providing access to the application model (including Activity and Service APIs);

android.provider to ease developer access to certain standard Content Providers (such as 
the contacts database);

android.telephony allows to directly interact with the device’s phone stack in order to make, receive, and monitor phone calls, phone status, and SMS messages.

android.webkit features APIs for working with Web-based content, including a WebView control for embedding browsers in your activities and a cookie manager.

In addition to these core APIs some advanced libraries for more complex applications are available. Their detailed features and functionalities depend on the specific device. Let’s list some of them:

android.location gives applications access to the device’s current physical location, using whatever position-fixing hardware or technology is available on the device;

android.media provides support for playback and recording of audio and video media files, including streamed media;

android.opengl offers a powerful 3D rendering engine using the OpenGL ES API for creating dynamic 3D user interfaces for your applications;

android.hardware, where available, exposes sensor hardware including the camera, accelerometer, and compass sensors;

android.bluetooth, android.net.wifi , and android.telephony provide low-level access to the hardware platform, including Bluetooth, Wi-Fi, and telephony.