Component Of Android Project

Project Component

Activity:  Activity Detail  

 An activity is a single, focused thing that the user can do. Almost all activities interact with the user, so the Activity class takes care of creating a window for you in which you can place your UI with setContentView(View).

Broadcast Receiver:

 A broadcast receiver (short receiver) is an Android component which allows you to register for system or application events. All registered receivers for an event will be notified by the Android run time once this event happens.

For example applications can register for the ACTION_BOOT_COMPLETED system event which is fired once the Android system has completed the boot process.

Services:

A service is a component which runs in the background, without direct interaction with the user. As the service has no user interface it is not bound to the life cycle of an activity.

Services are used for repetitive and potential long running operations, like Internet downloads, checking for new data, data processing, updating content providers and the like.

Services run with a higher priority than inactive or invisible activities and therefore it is less likely that the Android system terminates them. Services can also be configured to be restarted, if they get terminated by the Android system once sufficient system resources are available again.

It is possible to assign services the same priority as foreground activities. In this case it is required to have a visible notification active for the related service. It is frequently used for services which play videos or music.

Content Provider:

A content provider component supplies data from one application to others on request. Such requests are handled by the methods of the ContentResolver class. A content provider can use different ways to store its data and the data can be stored in a database, in files, or even over a network.

Each Android applications runs in its own process with its own permissions which keeps an application data hidden from another application. But sometimes it is required to share data across applications. This is where content providers become very useful.

Content providers let you centralize content in one place and have many different applications access it as needed. A content provider behaves very much like a database where you can query it, edit its content, as well as add or delete content usingg insert(), update(), delete(), and query() methods. In most cases this data is stored in an SQlite database.