Broadcast receiving app:

MainActivity.javaExampleBroadcastReceiver.javaAndroidManifest.xml
package com.codinginflow.broadcastexample;

import android.content.IntentFilter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {
    ExampleBroadcastReceiver exampleBroadcastReceiver = new ExampleBroadcastReceiver();

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

        IntentFilter filter = new IntentFilter("com.codinginflow.EXAMPLE_ACTION");
        registerReceiver(exampleBroadcastReceiver, filter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(exampleBroadcastReceiver);
    }
}

package com.codinginflow.broadcastexample;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

public class ExampleBroadcastReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        if ("com.codinginflow.EXAMPLE_ACTION".equals(intent.getAction())) {
            String receivedText = intent.getStringExtra("com.codinginflow.EXTRA_TEXT");
            Toast.makeText(context, receivedText, Toast.LENGTH_SHORT).show();
        }
    }
}

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

Broadcast sending app (BroadcastSender):

activity_main.xmlMainActivity.java
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical"
    android:padding="16dp"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Message"
        android:textSize="20sp" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="sendBroadcast"
        android:text="Send Broadcast" />

</LinearLayout>

package com.codinginflow.broadcastsender;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private TextView textView;

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

        textView = findViewById(R.id.text_view);
    }

    public void sendBroadcast(View v) {
        Intent intent = new Intent("com.codinginflow.EXAMPLE_ACTION");
        intent.putExtra("com.codinginflow.EXTRA_TEXT", "Broadcast received");
        sendBroadcast(intent);
    }

    private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String receivedText = intent.getStringExtra("com.codinginflow.EXTRA_TEXT");
            textView.setText(receivedText);
        }
    };

    @Override
    protected void onStart() {
        super.onStart();
        IntentFilter filter = new IntentFilter("com.codinginflow.EXAMPLE_ACTION");
        registerReceiver(broadcastReceiver, filter);
    }

    @Override
    protected void onStop() {
        super.onStop();
        unregisterReceiver(broadcastReceiver);
    }
}