Android Alarm Clock Tutorial

This Android tutorial will walk you through to create an alarm clock Android application. This alarm app is planned to be minimalistic and usable. It can set alarm for one occurrence for the coming day. You will get alarm ring sound, a notification message and a message in the app UI. This application and device can be idle or sleeping when the alarm triggers.

We will be using the AlarmManager API to set and ring the alarm notification. We will have a TimePicker component and a toggle switch in the UI to set the alarm time.

Android Alarm Clock Application

Application is planned to be simple as possible and you can use this as a base framework and enhance it by adding fancy features.

1. Android Manifest

AndroidManifest.xml

We need to give uses-permission for WAKE_LOCK, other than that the AndroidManifest.xml is pretty standard one. Just need to include the service and receiver.

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

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

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">
        <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>
        <service
            android:name=".AlarmService"
            android:enabled="true" />
        <receiver android:name=".AlarmReceiver" />
    </application>
</manifest>

2. Android Activity

activity_my.xml

The Android Activity is designed to be simple. We have a TimePicker component followed by a ToggleButton. That’s it. Choose the time to set the alarm and toggle the switch to on. The alarm will work.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MyActivity">

    <TimePicker
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/alarmTimePicker"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />


    <ToggleButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Alarm On/Off"
        android:id="@+id/alarmToggle"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/alarmTimePicker"
        android:onClick="onToggleClicked" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text=""
        android:id="@+id/alarmText"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        android:layout_below="@+id/alarmToggle" />

</RelativeLayout>

AlarmActivity.java

AlarmActivity uses the AlarmManager to set the alarm and send notification on alarm trigger.

package com.javapapers.androidalarmclock;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
import android.widget.TimePicker;
import android.widget.ToggleButton;

import java.util.Calendar;

public class AlarmActivity extends Activity {

    AlarmManager alarmManager;
    private PendingIntent pendingIntent;
    private TimePicker alarmTimePicker;
    private static AlarmActivity inst;
    private TextView alarmTextView;

    public static AlarmActivity instance() {
        return inst;
    }

    @Override
    public void onStart() {
        super.onStart();
        inst = this;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
        alarmTimePicker = (TimePicker) findViewById(R.id.alarmTimePicker);
        alarmTextView = (TextView) findViewById(R.id.alarmText);
        ToggleButton alarmToggle = (ToggleButton) findViewById(R.id.alarmToggle);
        alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
    }

    public void onToggleClicked(View view) {
        if (((ToggleButton) view).isChecked()) {
            Log.d("MyActivity", "Alarm On");
            Calendar calendar = Calendar.getInstance();
            calendar.set(Calendar.HOUR_OF_DAY, alarmTimePicker.getCurrentHour());
            calendar.set(Calendar.MINUTE, alarmTimePicker.getCurrentMinute());
            Intent myIntent = new Intent(AlarmActivity.this, AlarmReceiver.class);
            pendingIntent = PendingIntent.getBroadcast(AlarmActivity.this, 0, myIntent, 0);
            alarmManager.set(AlarmManager.RTC, calendar.getTimeInMillis(), pendingIntent);
        } else {
            alarmManager.cancel(pendingIntent);
            setAlarmText("");
            Log.d("MyActivity", "Alarm Off");
        }
    }

    public void setAlarmText(String alarmText) {
        alarmTextView.setText(alarmText);
    }
}

3. Alarm Receiver

AlarmReceiver.java

AlarmReceiver is a WakefulBroadcasReceiver, this is the one that receives the alarm trigger on set time. From here we initiate different actions to notify the user as per our choice. I have given three type of notifications, first show a message to user in the activity UI, second play the alarm ringtone and third send an Android notification message. So this is the place to add enhancement for different types of user notifications.

package com.javapapers.androidalarmclock;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.media.Ringtone;
import android.media.RingtoneManager;
import android.net.Uri;
import android.support.v4.content.WakefulBroadcastReceiver;

public class AlarmReceiver extends WakefulBroadcastReceiver {

    @Override
    public void onReceive(final Context context, Intent intent) {
        //this will update the UI with message
        AlarmActivity inst = AlarmActivity.instance();
        inst.setAlarmText("Alarm! Wake up! Wake up!");

        //this will sound the alarm tone
        //this will sound the alarm once, if you wish to
        //raise alarm in loop continuously then use MediaPlayer and setLooping(true)
        Uri alarmUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
        if (alarmUri == null) {
            alarmUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        }
        Ringtone ringtone = RingtoneManager.getRingtone(context, alarmUri);
        ringtone.play();

        //this will send a notification message
        ComponentName comp = new ComponentName(context.getPackageName(),
                AlarmService.class.getName());
        startWakefulService(context, (intent.setComponent(comp)));
        setResultCode(Activity.RESULT_OK);
    }
}

4. Alarm Notification Message

AlarmService.java

The receiver will start the following IntentService to send a standard notification to the user.

package com.javapapers.androidalarmclock;

import android.app.IntentService;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.support.v4.app.NotificationCompat;
import android.util.Log;

public class AlarmService extends IntentService {
    private NotificationManager alarmNotificationManager;

    public AlarmService() {
        super("AlarmService");
    }

    @Override
    public void onHandleIntent(Intent intent) {
        sendNotification("Wake Up! Wake Up!");
    }

    private void sendNotification(String msg) {
        Log.d("AlarmService", "Preparing to send notification...: " + msg);
        alarmNotificationManager = (NotificationManager) this
                .getSystemService(Context.NOTIFICATION_SERVICE);

        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                new Intent(this, AlarmActivity.class), 0);

        NotificationCompat.Builder alamNotificationBuilder = new NotificationCompat.Builder(
                this).setContentTitle("Alarm").setSmallIcon(R.drawable.ic_launcher)
                .setStyle(new NotificationCompat.BigTextStyle().bigText(msg))
                .setContentText(msg);


        alamNotificationBuilder.setContentIntent(contentIntent);
        alarmNotificationManager.notify(1, alamNotificationBuilder.build());
        Log.d("AlarmService", "Notification sent.");
    }
}

AndroidAlarmClock