package com.Reminder;
import java.util.Calendar;
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.Button;
/**
* trigger the Broadcast event and set the alarm
*/
public class ReminderSetting extends Activity {
  Button btnEnable;
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    /* create a button. When you click the button, the alarm clock is enabled */
    btnEnable=(Button)findViewById(R.id.btnEnable);
    btnEnable.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        setReminder(true);
      }
    });
  }
  /**
   * Set the alarm 
   * 
   * @param b whether enable the Alarm clock or not 
   */
  private void setReminder(boolean b) {
    // get the AlarmManager instance 
    AlarmManager am= (AlarmManager) getSystemService(ALARM_SERVICE);
    // create a PendingIntent that will perform a broadcast
    PendingIntent pi= PendingIntent.getBroadcast(ReminderSetting.this, 0, new Intent(this,MyReceiver.class), 0);
    if(b){
      // just use current time as the Alarm time. 
      Calendar c=Calendar.getInstance();
      // schedule an alarm
      am.set(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), pi);
    }
    else{
      // cancel current alarm
      am.cancel(pi);
    }
  }
}

package com.Reminder;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
/**
* Receive the broadcast and start the activity that will show the alarm
*/
public class MyReceiver extends BroadcastReceiver {
  /**
   * called when the BroadcastReceiver is receiving an Intent broadcast.
   */
  @Override
  public void onReceive(Context context, Intent intent) {
    /* start another activity - MyAlarm to display the alarm */
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    intent.setClass(context, MyAlarm.class);
    context.startActivity(intent);
  }
}

<receiver android:name=".MyReceiver">  
    <intent-filter> 
    <action android:name= "com.Reminder.MyReceiver" /> 
  </intent-filter> 
</receiver>

package com.Reminder;
import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore.Audio;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
/**
* Display the alarm information 
*/
public class MyAlarm extends Activity {
  /**
   * An identifier for this notification unique within your application
   */
  public static final int NOTIFICATION_ID=1; 
  @Override
  protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.my_alarm);
    // create the instance of NotificationManager
    final NotificationManager nm=(NotificationManager) getSystemService(NOTIFICATION_SERVICE);
    // create the instance of Notification
    Notification n=new Notification();
    /* set the sound of the alarm. There are two way of setting the sound */
     // n.sound=Uri.parse("file:///sdcard/alarm.mp3");
    n.sound=Uri.withAppendedPath(Audio.Media.INTERNAL_CONTENT_URI, "20");
    // Post a notification to be shown in the status bar
    nm.notify(NOTIFICATION_ID, n);
    /* display some information */
    TextView tv=(TextView)findViewById(R.id.tvNotification);
    tv.setText("Hello, it's time to bla bla...");
    /* the button by which you can cancel the alarm */
    Button btnCancel=(Button)findViewById(R.id.btnCancel);
    btnCancel.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View arg0) {
        nm.cancel(NOTIFICATION_ID);
        finish();
      }
    });
  }
}