Broadcast Receiver

In Android, Broadcast Receiver is a process of broadcasting particular event and receiver performs an action related to that event.

When system/application broadcasts event (An event consists of particular message/intent), it triggers the receiver to execute service, activity or other application.

Broadcast Receiver not actively running in memory.

Ex: Create a subclass of the BroadcastReceiver class.

public class ReceiverCls extends BroadcastReceiver  {

         @Override
         public void onReceive(Context context, Intent intent)  {
               Toast.makeText(context, intent.toString(), Toast.LENGTH_LONG).show();
          }
      }
//Here, intent.toString() returns a String like, Intent { act=Custom_Action cmp=com.YourPkgName/.ReceiverCls }

Now, We need to register Receiver class in AndroidManifest file.

<application>
     <receiver android:name="ReceiverCls">
            <intent-filter>
                <action android:name="Custom_Action"/>
                <action android:name="android.intent.action.BOOT_COMPLETED"/>
            </intent-filter>
     </receiver>
</application>

As shown in the code, there are two actions for the ReceiverCls class in which "android.intent.action.BOOT_COMPLETED" action provided by Android itself and another is custom action which performs when button clicked.

Now, we add a button in the layout file.

<Button android:onClick="custom_intent" />

Now, Implement the custom_intent() method in a subclass of Activity class.

public void custom_intent(View v) {
  Intent i=new Intent();
  i.setAction("Custom_Action");
  sendBroadcast(i);
}