Android Application component ?

                            What is a Android  Component ?

What is a Android Component?

There are four components that can use within android application. These components are coupled by the application AndroidManifest.xml that describes each component of the application and how they interact.

Activity

The activity is a building block of user interface. For example, an email application might have one Registration activity, and another Login activity. If an application has more than one activity, then one of them should be marked as the activity that is presented when the application is launched.

Public class MainActivity extends Activity {

}

Service

A service is a component that runs in the background to perform long-running operations. For example, a service might play music in the background while the user is in a different application, or it might fetch data over the network without blocking user interaction with an activity.

Public class MyBootLoader extends Service {

}

Broadcast Receivers

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 are notified by the Android runtime 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.

Public class MyAlert extends BroadcastReceiver {

   Public void onReceive (context, intent){}

}

Content Providers

The ContentProvider used to get data from central repository. Android application contains content provider to provide data to other applications. Content provider show data to content resolver as one or many tables that will show same as relational database.
Android provide Number of content providers that store common data such as contact information’s, item List information, and media files etc.

Public class MyProvider extends ContentProvider {

   Public void onCreate (){}

}