I was learning concept of broadcast receivers and I wanted to make a project with which I can demonstrate triggering specific implicit receiver class which is kind of explicit broadcast.

I made 2 apps the sender app and receiver app for demonstration :

BROADCAST SENDER's MAIN ACTIVITY :

public class MainActivity extends AppCompatActivity {

//Declaring our views
TextView senderTextView;
Button sendButton;

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

    //initializing views
    senderTextView = findViewById(R.id.senderTextView);
    sendButton = findViewById(R.id.sendButton);
    //Setting onClick Listener on sendButton
    sendButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            //Calling Broadcast Method
            Broadcast();
        }
    });

}
//Broadcast Method
private void Broadcast(){
    //Creating private broadcast intent
    Intent intent = new Intent("com.example.broadcastreceiver.PRIVATE_BROADCAST");
    //Here we are going to find all the apps in our mobile that have registered for this broadcast in their manifests
    //This will help us to find packages or apps registered for com.example.PRIVATE_BROADCAST action
    PackageManager packageManager = getPackageManager();
    //queryBroadcastReceivers of package manager will query all the receivers having intent filter for "com.example.PRIVATE_BROADCAST" action
    //and store receivers info in resolveInfoList
    List<ResolveInfo> resolveInfoList = packageManager.queryBroadcastReceivers(intent,0);
    //Now we will iterate over this list to find our specific receiver and trigger it
    //for each info in resolveInfoList
    for (ResolveInfo info : resolveInfoList){
        //if info's receiver class name is com.example.broadcastreceiver.CustomBroadcastReceiver (which is our receiver class in receiver app)
        if(info.activityInfo.name.equals("com.example.broadcastreceiver.CustomBroadcastReceiver")){
            //then use this info to get package name and receiver class name to make a componentName
            ComponentName componentName = new ComponentName(info.activityInfo.packageName,info.activityInfo.name);
            //now set this componentName to our intent
            intent.setComponent(componentName);
        }
    }
    //Sending our private broadcast to our android mobile
    sendBroadcast(intent);
    //setting textView
    senderTextView.setText("Broadcast Sent!");
}

BROADCAST RECEIVER'S MANIFEST :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.example.broadcastreceiver">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.BroadcastReceiver"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <receiver
            android:name=".CustomBroadcastReceiver"
            android:exported="true">
            <intent-filter>
                <action android:name="com.example.broadcastreceiver.PRIVATE_BROADCAST"/>
            </intent-filter>
        </receiver>

    </application>

</manifest>

BROADCAST RECEIVER's CustomBroadcastReceiver Class :

public class CustomBroadcastReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {
    
        //Making a toast when broadcast is received
        Toast.makeText(context, "Broadcast Receiver App : Custom Broadcast Receiver Triggered" , Toast.LENGTH_SHORT).show();

}

BroadcastReceiver's Mainactivity has nothing.

This should trigger the toast in CustomBroadcastReciever class of Broadcast Receiver App but due to some reason toast is not appearing please help.

Thanks in advance :)

CodePudding user response：

Just created a demo app that works:

In app1, send the broadcast like this (obviously change package names):

public void sendBroadcast() {
    Intent broadcastIntent = new Intent("com.example.testimplicitbroadcastreceiver.PRIVATE_BROADCAST");
    broadcastIntent.setComponent(new ComponentName("com.example.testimplicitbroadcastreceiver",
            "com.example.testimplicitbroadcastreceiver.CustomBroadcastReceiver"));
    sendBroadcast(broadcastIntent);
}

In app2's manifest, register the BroadcastReceiver:

<receiver
    android:name=".CustomBroadcastReceiver"
    android:exported="true">
    <intent-filter>
        <action android:name="com.example.testimplicitbroadcastreceiver.PRIVATE_BROADCAST"/>
    </intent-filter>
</receiver>

Voila, now app2 will receive your Broadcast in the CustomBroadcastReceiver.