Learn how to handle system-wide events in your application with Android BroadcastReceiver. Our tutorial will guide you step-by-step on how to create and register a BroadcastReceiver. Start now and make your app more responsive!
What is an Android BroadcastReceiver?
An Android BroadcastReceiver is a dormant component that listens for system-wide broadcast events or intents. When one of these events occurs, the BroadcastReceiver activates the application by either creating a status bar notification or performing a task. Unlike Activities, a BroadcastReceiver has no user interface. It delegates tasks to services based on the received intents.
Important System Intents
Some important system-wide intents are:
android.intent.action.BATTERY_LOW: Indicates low battery level.android.intent.action.BOOT_COMPLETED: Sent after the system finishes booting.android.intent.action.CALL: Makes a call.android.intent.action.DATE_CHANGED: Date has changed.android.intent.action.REBOOT: Device is rebooting.android.net.conn.CONNECTIVITY_CHANGE: Network connection has changed or reset.
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Setting up a BroadcastReceiver in Android
To set up a BroadcastReceiver, two steps are required:
- Creating a BroadcastReceiver
- Registering the BroadcastReceiver
Creating a BroadcastReceiver
An example of implementing a BroadcastReceiver:
public class MyReceiver extends BroadcastReceiver {
public MyReceiver() {
}
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "Action: " + intent.getAction(), Toast.LENGTH_SHORT).show();
}
}The BroadcastReceiver is an abstract class, and the onReceive() method is called when an event occurs. The intent object contains all the additional data.
Registering the BroadcastReceiver
A BroadcastReceiver can be registered in two ways:
- In the AndroidManifest.xml:
<receiver android:name=".ConnectionReceiver">
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
</intent-filter>
</receiver>- Programmatically:
IntentFilter filter = new IntentFilter();
filter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
MyReceiver myReceiver = new MyReceiver();
registerReceiver(myReceiver, filter);To deactivate a BroadcastReceiver in the onStop() or onPause() of the Activity, use:
@Override
protected void onPause() {
unregisterReceiver(myReceiver);
super.onPause();
}Sending Broadcast Intents
To send an intent to all related BroadcastReceivers:
Intent intent = new Intent();
intent.setAction("com.journaldev.CUSTOM_INTENT");
sendBroadcast(intent);Don't forget to add the above action in the intent filter of the manifest or programmatically.
Example of an Android Application
Here is an example of an application that listens for network changes and processes a custom intent:
activity_main.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send Broadcast"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>MainActivity.java:
public class MainActivity extends AppCompatActivity {
ConnectionReceiver receiver;
IntentFilter intentFilter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
receiver = new ConnectionReceiver();
intentFilter = new IntentFilter("com.journaldev.broadcastreceiver.SOME_ACTION");
}
@Override
protected void onResume() {
super.onResume();
registerReceiver(receiver, intentFilter);
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(receiver);
}
public void someMethod(View view) {
Intent intent = new Intent("com.journaldev.broadcastreceiver.SOME_ACTION");
sendBroadcast(intent);
}
}AndroidManifest.xml:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.journaldev.broadcastreceiver">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
android:allowBackup="true"
android:label="@string/app_name">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name=".ConnectionReceiver">
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
</intent-filter>
</receiver>
</application>
</manifest>ConnectionReceiver.java:
public class ConnectionReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equals("com.journaldev.broadcastreceiver.SOME_ACTION"))
Toast.makeText(context, "SOME_ACTION is received", Toast.LENGTH_LONG).show();
else {
ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null && activeNetwork isConnectedOrConnecting();
Toast.makeText(context, isConnected ? "Network is connected" : "Network is changed or reconnected", Toast.LENGTH_LONG).show();
}
}
}Conclusion
With this knowledge, you can now create your own BroadcastReceivers and integrate them into your Android applications. These allow you to respond to system-wide events and act accordingly.
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