Описание тега android-broadcast

A broadcast intent on the Android platform is a special intent which is often invoked by the system on an event and catched by a BroadcastReceiver.

You can either dynamically register an instance of this class with Context.registerReceiver() or statically publish an implementation through the <receiver> tag in your AndroidManifest.xml.

There are following two important steps to make BroadcastReceiverworks for the systen broadcasted intents:

• Creating the BroadcastReceiver.
• Registering Broadcast Receiver

Creating the BroadcastReceiver

A broadcast receiver is implemented as a subclass of BroadcastReceiver class and overriding the onReceive() method where each message is received as a Intent object parameter.

public class MyReceiver extends BroadcastReceiver {
   @Override
   public void onReceive(Context context, Intent intent) {
      Toast.makeText(context, "Intent Detected.", Toast.LENGTH_LONG).show();
   }
}

Registering Broadcast Receiver

An application listens for specific broadcast intents by registering a broadcast receiver in AndroidManifest.xml file. Consider we are going to register MyReceiver for system generated event ACTION_BOOT_COMPLETED which is fired by the system once the Android system has completed the boot process.

<application
   android:icon="@drawable/ic_launcher"
   android:label="@string/app_name"
   android:theme="@style/AppTheme" >

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

Now whenever your Android device gets booted, it will be intercepted by BroadcastReceiver MyReceiver and implemented logic inside onReceive() will be executed.

See also the documentation about Intents and Intent Filters.