How to Send BroadCast from one app to another app

I have App A and App B. In App A I want to send broadcast to App B. This is the code for App A:

final Intent intent = new Intent();
intent.setAction("com.pkg.perform.Ruby");
intent.putExtra("KeyName", "code1id");
intent.setComponent(new ComponentName("com.pkg.AppB", "com.pkg.AppB.MainActivity"));
sendBroadcast(intent);

And in App B - In MainActivity, I have MyBroadCastReceiver Class.

public class MainActivity extends Activity {
    private MyBroadcastReceiver MyReceiver;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // Receive broadcast from External App
        IntentFilter intentFilter = new IntentFilter("com.pkg.perform.Ruby");
        MyReceiver = new MyBroadcastReceiver();
        if(intentFilter != null)
        {
            registerReceiver(MyReceiver, intentFilter);
        }
    }

    public class MyBroadcastReceiver extends BroadcastReceiver
    {
        @Override
        public void onReceive(Context context, Intent intent) {
            Toast.makeText(MainActivity.this, "Data Received from External App", Toast.LENGTH_SHORT).show();
        }
    }
   
    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(MyReceiver != null)
            unregisterReceiver(MyReceiver);
    }
}

I am getting the error - Receiver is not registered.

First thing first declare the receiver in app B in the manifest file like this:

<receiver android:name=".MyBroadcastReceiver"
	android:enabled="true"
	android:exported="true">
		<intent-filter>
		  <action android:name="com.pkg.perform.Ruby" />
		</intent-filter>
</receiver>

when sending the broadcast add FLAG_INCLUDE_STOPPED_PACKAGES flag to the intent [src] because when you broadcast from app A to app B , app B might not be running, this flag insures that the broadcast reachs out even apps not running:

> FLAG_INCLUDE_STOPPED_PACKAGES flag is added to the intent before it > is sent to indicate that the intent is to be allowed to start a > component of a stopped application.

intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);

In your case it will be like this:

    final Intent intent=new Intent();
    intent.setAction("com.pkg.perform.Ruby");
    intent.putExtra("KeyName","code1id");
    intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
    intent.setComponent(  
        new ComponentName("com.pkg.AppB","com.pkg.AppB.MyBroadcastReceiver"));  
    sendBroadcast(intent);

In App A: Send the broadcast here.

 final Intent i= new Intent();
 i.putExtra("data", "Some data");
 i.setAction("com.pkg.perform.Ruby");
 i.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
 getApplicationContext().sendBroadcast(i);

In App B manifest

 <receiver  android:name=".MyBroadcastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.pkg.perform.Ruby" />
            </intent-filter>
        </receiver>

In App B MainActivity: register the receiver oncreate(), and unregister onDestroy()

 public class MainActivity extends AppCompatActivity
 {
      private MyBroadcastReceiver MyReceiver;
    
       @Override
       protected void onCreate(Bundle savedInstanceState)
       {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            MyReceiver = new MyBroadcastReceiver();
            IntentFilter intentFilter = new IntentFilter("com.pkg.perform.Ruby");
            if(intentFilter != null)
            {
               registerReceiver(MyReceiver, intentFilter);
            }
       }

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

In App B BroadcastReceiver

public class MyBroadcastReceiver extends BroadcastReceiver
{
    @Override
    public void onReceive(Context context, Intent intent)
    {
        String data = intent.getStringExtra("data");
        Log.i("BR" ,"Data received:  " + data);
    }
}

There may be two cases :

> 1. Your appB is not running, hence the activity is not instantiated, and so the receiver is not registered. > 2. Your activity is destroyed, means that you have unregistered your receiver that you registered via registerReceiver() in onCreate()

Solution :

> Register your broadcast receiver in manifest.

Inside manifest of appB :

<receiver android:name=".MyBroadcastReceiver">
    <intent-filter>
        <action android:name="com.pkg.perform.Ruby" />
    </intent-filter>
</receiver>

And comment out the line in appA

intent.setComponent(new ComponentName("com.pkg.AppB","com.pkg.AppB.MainActivity"));

Write the logic in MyBroadcastReceiver to display relevant data/launch new activity

MyReceiver is class not object. Create

myReceiver = new MyReceiver(); 

and put...........

registerReceiver(myReceiver,intentFilter);

If this helps some one and it works for me

In App A in activity or in a content provider-

  Intent intent = new Intent("Updated");
  intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
  intent.setComponent (new
  ComponentName "com.exam.appA",
  "com.exam.appA.DbaseChanged"));
  getContext().sendBroadcast(intent);

In App B in the manifest

      <receiver
        android:name=".DbaseChanged"
        android:enabled="true"
        android:exported="true">
        <intent-filter>
            <action android:name="Updated" />
        </intent-filter>
      </receiver>

In App B Broadcast receiver class-

    public class DbaseChanged extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent
     intent)   {

           String act = intent.getAction();
           if(act != null && act.equals("Updated")  )
            {
                Toast.makeText(context, act ,
              Toast.LENGTH_SHORT).show();

            }

            }
       }

I needed to call setPackage("package_name") to ensure explicitness when I registered the broadcast receiver in the Manifest. I was then able to receive the data even if the app was closed completely.

// sending app sends broadcast
Intent intent = new Intent(ACTION_RECOMMEND);
intent.putExtra(LISTEN_RECOMMENDATION, "Triggered - Jhene Aiko");
intent.putExtra(WATCH_RECOMMENDATION, "Goblin - Kim Go-eun");
intent.setPackage("com.example.package.receiverapp");
sendBroadcast(intent);


//receiving app manifest registers receiver
<receiver
   android:name=".ManifestRegisteredBroadcastReceiver"
   android:exported="true">
   <intent-filter>
       <action android:name="com.random.action.RECOMMEND" />
   </intent-filter>
</receiver>

I didn't need to add intent.setPackage(package_name) when registering the receiver via an activity, but this also meant that I couldn't get the data if the activity was destroyed (app closed, app in background for long period)