How to use Broadcast Receiver

The Android platform provides a lot of pre-defined services, usually exposed via a Manager class. In this chapter we will use the AlertManager and VibratorManager. The alarm manager will in our example our own broadcast receiver.

Create a new project "de.vogella.android.alarm" with the activity "AlarmActivity". Create the following layout.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical" android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 

<EditText android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/time" android:hint="Number of seconds" android:inputType="numberDecimal"></EditText><Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/ok" android:onClick="startAlert" android:text="Start Counter"></Button>

</LinearLayout>

  

Create the following broadcast receiver class. This class will get the Vibrator service.

package de.vogella.android.alarm;

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

public class MyBroadcastReceiver extends BroadcastReceiver {
 @Override
 public void onReceive(Context context, Intent intent) {
  Toast.makeText(context, "Don't panik but your time is up!!!!.",
    Toast.LENGTH_LONG).show();
  // Vibrate the mobile phone
  Vibrator vibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);
  vibrator.vibrate(2000);
 }

}

  

Maintain this class as broadcast receiver in "AndroidManifest.mf" and allow the vibrate authorization.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="de.vogella.android.alarm" android:versionCode="1"
 android:versionName="1.0">
 <application android:icon="@drawable/icon" android:label="@string/app_name">
  <activity android:name=".AlarmActivity" android:label="@string/app_name">
   <intent-filter>
    <action android:name="android.intent.action.MAIN" />
    <category android:name="android.intent.category.LAUNCHER" />
   </intent-filter>
  </activity>
  <receiver android:name=".MyBroadcastReceiver" android:enabled="true">
  </receiver>
 </application>
 <uses-sdk android:minSdkVersion="8" />


<uses-permission android:name="android.permission.VIBRATE"></uses-permission>
</manifest> 


  

Now define your main Activitiy. This activity will create an Intent for the Broadcast receiver and get the AlarmManager service.

package de.vogella.android.alarm;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class AlarmActivity extends Activity {
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
 }

 public void startAlert(View view) {
  EditText text = (EditText) findViewById(R.id.time);
  int i = Integer.parseInt(text.getText().toString());
  Intent intent = new Intent(this, MyBroadcastReceiver.class);
  PendingIntent pendingIntent = PendingIntent.getBroadcast(
    this.getApplicationContext(), 234324243, intent, 0);
  AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
  alarmManager.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis()
    + (i * 1000), pendingIntent);
  Toast.makeText(this, "Alarm set in " + i + " seconds",
    Toast.LENGTH_LONG).show();
 }

}