Wear OS AlarmManager

A new platform called Wear OS was created especially for wearable technology. Despite being focused on Android, it has a distinctive appearance and a range of special features. Users can build a list of things with a reminder time assigned to each task using the alarm manager on Wear OS application. It aids in keeping track of one's critical responsibilities. Also, it is helpful for starting and carrying out additional activities when used with broadcast receivers. Besides, it lessens one's reliance on timers or background processes that run all the time.

Access to the Android AlarmManager, which functions quite differently from iOS Local Notifications, is made available via this module.

Features

• Set a once off alarm
• Set a recurring alarm on set days of the week
• Disable and re-enable an alarm
• Play a looped ringtone for the alarm that is active
• Play a vibration effect for the alarm that is active
• Show a notification for the alarm this is active
• Dismiss or snooze an alarm

Components

• Time Picker
• Alarm Manager
• Broadcast Receivers
• Services
• Vibrator
• Ringtone
• Intent, Pending Intent and Intent Extras
• Manifest and Permissions
• Calendar
• MVVM Design Pattern
• LiveData, Observer and Repository

Steps to follow

Step 1: Capturing the Alarm Time

TimePicker is used to capture the alarm time and ToggleButton is added to set the alarm on or off. Initially, ToggleButton is set to off. It is set on when an alarm is set. In AlarmSet.java class onToggleClicked( ) method is implemented in which the current hour and the minute is set using the calendar.

The getCurrentHour() and getCurrentMinute() methods were required to retrieve the hour and minute from the TimePicker widget prior to Android API level 23. But now use the getHour() and getMinute() methods are used since the earlier methods have been deprecated.

Step 2: Scheduling an Alarm

The alarm is scheduled using the AlarmManager. The setExact(...) function on the AlarmManager with the arguments is used to schedule the alarm if it is not recurring. AlarmManager.RTC_WAKEUP alarm type (meaning it will wake up the device to fire the alarm if the screen is off), the time of the alarm in milliseconds and the pending intent previously created. If the alarm is recurring, it is scheduled using the AlarmManager.setRepeating(...) function with the parameters AlarmManager.RTC WAKEUP alarm type, the alarm's millisecond duration, the repeat interval (which is set to 1 day), and the previously established pending intent.

Sample Code:

alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, time, 30000, pendingIntent);

Step 3: Starting the Alarm Service

In this module's part, we'll use a BroadcastReceiver to record the Broadcast that the AlarmManager sends out when the pre-set alarm goes off. Once this broadcast is received, we will utilize it to activate an alarm service that will play a repeating alarm sound, display a notification, and vibrate the device. Broadcast receivers are an Android app component that allow us to listen to different events or broadcasts such as those generated by the Android operating system or Android apps.

In AlarmReceiver.java class onReceive() method is implemented. Here, we've implemented a default ringtone and vibration feature that activates when the alarm is set to go off.

We verify that the broadcast received is not the one that was transmitted while the device was booting in the onReceive() method of our broadcast receiver. If not, the broadcast is related to an alarm, and we get more information from the Intent to determine whether the alarm is reoccurring or not.

If the alarm is not a recurring alarm, we use the startService(...) method on the context and supply an Intent with the alarm's title to start the alarm service.

When an alarm is repeating, further checks are made in the broadcast's intent extras to see if the current day of the week is acceptable for the recurring alert. We won't activate the alarm service till such is the case.

Sample Code:

public void onReceive(Context context, Intent intent) {
        Vibrator v = (Vibrator) context.getSystemService(context.VIBRATOR_SERVICE);
        v.vibrate(5000);

        Toast.makeText(context, "Alarm!!", Toast.LENGTH_LONG).show();
        Uri alarmUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
        if (alarmUri == null) {
            alarmUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        }

        Ringtone r = RingtoneManager.getRingtone(context, alarmUri);
        r.play();

        context.startService(new Intent(context, Accelerometer.class));
    }

Step 4: Cancelling an Alarm

Using an AlarmManager to schedule an alarm, the procedure is quite similar to the process using an AlarmManager to cancel an alarm. We first get a reference to the __AlarmManager __by executing getSystemService(ALARM SERVICE) in the cancel() method.

Then, using the AlarmBroadcastReceiver, we build an intent and use it to generate a pending intent with a reference to the alarm id we specified when setting the alarm. The alarm will be cancelled once we use the AlarmManager's cancel(PendingIntent) method, handing it the PendingIntent we generated as a parameter.

Sample Code:

else {
            alarmManager.cancel(pendingIntent);
            Toast.makeText(AlarmSet.this, "Stop Alarm", Toast.LENGTH_SHORT).show();
        }

Wrapping Up

Android AlarmManager is a class that provides access to alarm services of the system. Alarm manager allows the users to create a list of items with a reminder time associated with each task. We basically have a means to handle time-based processes thanks to alarms.

Basically, an alarm has the qualities listed below:

• It can function independently of the application, which enables the alarm to start the event even if the device is dormant or the application is not open.
• The alarm executes intents at predetermined periods or times.
• It can be used in conjunction with broadcast receivers to carry out specific tasks or launch services.
• It helps in minimizing the resource requirements.
• Unless the alarm's forcibly stopped or the device resets, it will continue to run.

To get notification at a particular time with alarm manager in the android studio The following features are needed:

• Using speech to text convertor to creat event name from the user’s speech.
• Enter the description through text keyboard or use speech to text.
• Select the date and time on which event is scheduled and then submit.