[android] Programmatically register a broadcast receiver

I'd like to know what is the best practice/way of programmatically register a broadcast receiver. I want to register specific receivers according to user choice.

As the registration is done through the manifest file, I'm wondering if there's a proper way to achieve this in code.

In your onCreate method you can register a receiver like this:

private BroadcastReceiver receiver;

@Override
public void onCreate(Bundle savedInstanceState){

  // your oncreate code should be

  IntentFilter filter = new IntentFilter();
  filter.addAction("SOME_ACTION");
  filter.addAction("SOME_OTHER_ACTION");

  receiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
      //do something based on the intent's action
    }
  };
     registerReceiver(receiver, filter);
}

Remember to run this in the onDestroy method:

 @Override
 protected void onDestroy() {
  if (receiver != null) {
   unregisterReceiver(receiver);
   receiver = null;
  }
  super.onDestroy();
 }

for LocalBroadcastManager

   Intent intent = new Intent("any.action.string");
   LocalBroadcastManager.getInstance(context).
                                sendBroadcast(intent);

and register in onResume

LocalBroadcastManager.getInstance(
                    ActivityName.this).registerReceiver(chatCountBroadcastReceiver, filter);

and Unregister it onStop

LocalBroadcastManager.getInstance(
                ActivityName.this).unregisterReceiver(chatCountBroadcastReceiver);

and recieve it ..

mBroadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            Log.e("mBroadcastReceiver", "onReceive");
        }
    };

where IntentFilter is

 new IntentFilter("any.action.string")

Create a broadcast receiver

[BroadcastReceiver(Enabled = true, Exported = false)]

public class BCReceiver : BroadcastReceiver
{

    BCReceiver receiver;

    public override void OnReceive(Context context, Intent intent)
    {
        //Do something here
    }
}

From your activity add this code:

LocalBroadcastManager.getInstance(ApplicationContext)
    .registerReceiver(receiver, filter);

According to Listening For and Broadcasting Global Messages, and Setting Alarms in Common Tasks and How to Do Them in Android:

If the receiving class is not registered using in its manifest, you can dynamically instantiate and register a receiver by calling Context.registerReceiver().

Take a look at registerReceiver (BroadcastReceiver receiver, IntentFilter filter) for more info.

One important point that people forget to mention is the life time of the Broadcast Receiver. The difference of programmatically registering it from registering in AndroidManifest.xml is that. In the manifest file, it doesn't depend on application life time. While when programmatically registering it it does depend on the application life time. This means that if you register in AndroidManifest.xml, you can catch the broadcasted intents even when your application is not running.

Edit: The mentioned note is no longer true as of Android 3.1, the Android system excludes all receiver from receiving intents by default if the corresponding application has never been started by the user or if the user explicitly stopped the application via the Android menu (in Manage ? Application). https://developer.android.com/about/versions/android-3.1.html

This is an additional security feature as the user can be sure that only the applications he started will receive broadcast intents.

So it can be understood as receivers programmatically registered in Application's onCreate() would have same effect with ones declared in AndroidManifest.xml from Android 3.1 above.

Define a broadcast receiver anywhere in Activity/Fragment like this:

mReceiver = new BroadcastReceiver() {
 @Override
 public void onReceive(Context context, Intent intent) {
     Log.d(TAG," onRecieve"); //do something with intent
   }
 };

Define IntentFilter in onCreate()

mIntentFilter=new IntentFilter("action_name");

Now register the BroadcastReciever in onResume() and Unregister it in onPause() [because there is no use of broadcast if the activity is paused].

@Override
protected void onResume() {
     super.onResume();
     registerReceiver(mReceiver, mIntentFilter);
}

@Override
protected void onPause() {
    if(mReceiver != null) {
            unregisterReceiver(mReceiver);
            mReceiver = null;
    }
    super.onPause();
}

For detail tutorial, have a look at broadcast receiver-two ways to implement.

Two choices

1) If you want to read Broadcast only when the Activity is visible then,

registerReceiver(...) in onStart() and unregisterReceiver(...) in onStop()

2) If you want to read Broadcast even if Activity is in Background then,

registerReceiver(...) in onCreate(...) and unregisterReceiver(...) in onDestroy()

Bonus:

If you are lazy

If you don't want to write boilerplate code for registering and unregistering a BroadcastReceiver again and again in each Activity then,

1. Create an abstract Activity
2. Write boilerplate code in Activity
3. Leave the implementation as abstract methods

Here is the code snippet:

Abstract Activity

public abstract class BasicActivity extends AppCompatActivity {

    private BroadcastReceiver broadcastReceiver;
    private IntentFilter filter;
    private static final String TAG = "BasicActivity";

    /**********************************************************************
    *                   Boilerplate code
    **********************************************************************/

    @Override
    public void onCreate(Bundle sis){
        super.onCreate(sis);
        broadcastReceiver = getBroadcastReceiver();
        filter = getFilter();
    }

    @Override
    public void onStart(){
        super.onStart();
        register();
    }

    @Override
    public void onStop(){
        super.onStop();
        unregister();
    }

    private void register(){
        registerReceiver(broadcastReceiver,filter);
    }

    private void unregister(){
        unregisterReceiver(broadcastReceiver);
    }

    /**********************************************************************
    *                   Abstract methods
    **********************************************************************/

    public abstract BroadcastReceiver getBroadcastReceiver();

    public abstract IntentFilter getFilter();

}

Using this approach you can write more boilerplate code such as writing common animations, binding to a service, etc.

See full code:

HERE

It is best practice to always supply the permission when registering the receiver, otherwise you will receive for any application that sends a matching intent. This can allow malicious apps to broadcast to your receiver.

package com.example.broadcastreceiver;


import android.app.Activity;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends Activity {

   UserDefinedBroadcastReceiver broadCastReceiver = new UserDefinedBroadcastReceiver();

   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
   }

   @Override
   public boolean onCreateOptionsMenu(Menu menu) {
      getMenuInflater().inflate(R.menu.main, menu);
      return true;
   }

   /**
    * This method enables the Broadcast receiver for
    * "android.intent.action.TIME_TICK" intent. This intent get
    * broadcasted every minute.
    *
    * @param view
    */
   public void registerBroadcastReceiver(View view) {

      this.registerReceiver(broadCastReceiver, new IntentFilter(
            "android.intent.action.TIME_TICK"));
      Toast.makeText(this, "Registered broadcast receiver", Toast.LENGTH_SHORT)
            .show();
   }

   /**
    * This method disables the Broadcast receiver
    *
    * @param view
    */
   public void unregisterBroadcastReceiver(View view) {

      this.unregisterReceiver(broadCastReceiver);

      Toast.makeText(this, "unregistered broadcst receiver", Toast.LENGTH_SHORT)
            .show();
   }
}