Using repeating Notifications using AlarmManager

Question

I'm trying to develop an app which requires scheduled notifications everyday at 7am, 11am and 7pm. And when user taps on the notification it takes the user to MainActivity.

I have a working code but it's showing random behavior. I have the following problems.

1) Every time I open MainActivity, it triggers the alarm manager and shows a notification even though it's only supposed to be triggered at 7am, 11am and 7pm.

2) Also, I think I'm somehow duplicating alarms every time I open the main activity. Everytime I setup the alarm, I cancel the pending intent and then setup again. Is this the correct way to do it?

Manifest.xml

<receiver android:name=".AlarmReceiver">
        <intent-filter>
            <action android:name="android.media.action.DISPLAY_NOTIFICATION" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </receiver>

MainActivity.java

AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
    Calendar cal = Calendar.getInstance();
    Calendar cal1 = Calendar.getInstance();
    Calendar cal2 = Calendar.getInstance();

    Intent notificationIntent = new Intent("android.media.action.DISPLAY_NOTIFICATION");
    notificationIntent.addCategory("android.intent.category.DEFAULT");

    PendingIntent broadcast = PendingIntent.getBroadcast(this, 100, notificationIntent, 0);
    PendingIntent broadcast1 = PendingIntent.getBroadcast(this, 101, notificationIntent, 0);
    PendingIntent broadcast2 = PendingIntent.getBroadcast(this, 102, notificationIntent, 0);

    cal.set(Calendar.HOUR_OF_DAY, 7);
    cal.set(Calendar.MINUTE, 0);
    alarmManager.cancel(broadcast);
    alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(),
            AlarmManager.INTERVAL_DAY, broadcast);

    cal1.set(Calendar.HOUR_OF_DAY, 11);
    cal1.set(Calendar.MINUTE, 0);
    alarmManager.cancel(broadcast1);
    alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(),
            AlarmManager.INTERVAL_DAY, broadcast1);

    cal2.set(Calendar.HOUR_OF_DAY, 19);
    cal2.set(Calendar.MINUTE, 0);
    alarmManager.cancel(broadcast2);
    alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(),
            AlarmManager.INTERVAL_DAY, broadcast2);

AlarmReceiver.java

@Override
public void onReceive(Context context, Intent intent) {
    String Text = getText();

    Resources res = context.getResources();

    Intent notificationIntent = new Intent(context, MainActivity.class);

    TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
    stackBuilder.addParentStack(MainActivity.class);
    stackBuilder.addNextIntent(notificationIntent);

    PendingIntent pendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);

    NotificationCompat.Builder builder = new NotificationCompat.Builder(context);

    Notification notification = builder.setSmallIcon(R.drawable.ic_menu_notify)
            .setTicker("Ticker")
            .setLargeIcon(BitmapFactory.decodeResource(res, R.mipmap.ic_launcher))
            .setContentTitle("Title")
            .setContentText(Text)
            .setAutoCancel(true)
            .setDefaults(Notification.DEFAULT_SOUND | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE)
            .setContentIntent(pendingIntent).build();

    NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
    notificationManager.notify(0, notification);
}