The question is relatively old, but I hope this post still might be relevant for others.
TL;DR: use AlarmManager to schedule a task, use IntentService, see the sample code here;
What this test-application(and instruction) is about:
Simple helloworld app, which sends you notification every 2 hours. Clicking on notification – opens secondary Activity in the app; deleting notification tracks.
When should you use it:
Once you need to run some task on a scheduled basis.
My own case: once a day, I want to fetch new content from server, compose a notification based on the content I got and show it to user.
What to do:
First, let’s create 2 activities: MainActivity, which starts notification-service and NotificationActivity, which will be started by clicking notification:
activity_main.xml
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:padding="16dp"> <Button android:id="@+id/sendNotifications" android:onClick="onSendNotificationsButtonClick" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Start Sending Notifications Every 2 Hours!" /> </RelativeLayout>
MainActivity.java
public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void onSendNotificationsButtonClick(View view) { NotificationEventReceiver.setupAlarm(getApplicationContext()); } }
and NotificationActivity is any random activity you can come up with. NB! Don’t forget to add both activities into AndroidManifest.
Then let’s create
WakefulBroadcastReceiver
broadcast receiver, I called NotificationEventReceiver in code above.Here, we’ll set up
AlarmManager
to firePendingIntent
every 2 hours (or with any other frequency), and specify the handled actions for this intent inonReceive()
method. In our case – wakefully startIntentService
, which we’ll specify in the later steps. ThisIntentService
would generate notifications for us.Also, this receiver would contain some helper-methods like creating PendintIntents, which we’ll use later
NB1! As I’m using
WakefulBroadcastReceiver
, I need to add extra-permission into my manifest:<uses-permission android:name="android.permission.WAKE_LOCK" />
NB2! I use it wakeful version of broadcast receiver, as I want to ensure, that the device does not go back to sleep during my
IntentService
‘s operation. In the hello-world it’s not that important (we have no long-running operation in our service, but imagine, if you have to fetch some relatively huge files from server during this operation). Read more about Device Awake here.NotificationEventReceiver.java
public class NotificationEventReceiver extends WakefulBroadcastReceiver { private static final String ACTION_START_NOTIFICATION_SERVICE = "ACTION_START_NOTIFICATION_SERVICE"; private static final String ACTION_DELETE_NOTIFICATION = "ACTION_DELETE_NOTIFICATION"; private static final int NOTIFICATIONS_INTERVAL_IN_HOURS = 2; public static void setupAlarm(Context context) { AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE); PendingIntent alarmIntent = getStartPendingIntent(context); alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, getTriggerAt(new Date()), NOTIFICATIONS_INTERVAL_IN_HOURS * AlarmManager.INTERVAL_HOUR, alarmIntent); } @Override public void onReceive(Context context, Intent intent) { String action = intent.getAction(); Intent serviceIntent = null; if (ACTION_START_NOTIFICATION_SERVICE.equals(action)) { Log.i(getClass().getSimpleName(), "onReceive from alarm, starting notification service"); serviceIntent = NotificationIntentService.createIntentStartNotificationService(context); } else if (ACTION_DELETE_NOTIFICATION.equals(action)) { Log.i(getClass().getSimpleName(), "onReceive delete notification action, starting notification service to handle delete"); serviceIntent = NotificationIntentService.createIntentDeleteNotification(context); } if (serviceIntent != null) { startWakefulService(context, serviceIntent); } } private static long getTriggerAt(Date now) { Calendar calendar = Calendar.getInstance(); calendar.setTime(now); //calendar.add(Calendar.HOUR, NOTIFICATIONS_INTERVAL_IN_HOURS); return calendar.getTimeInMillis(); } private static PendingIntent getStartPendingIntent(Context context) { Intent intent = new Intent(context, NotificationEventReceiver.class); intent.setAction(ACTION_START_NOTIFICATION_SERVICE); return PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT); } public static PendingIntent getDeleteIntent(Context context) { Intent intent = new Intent(context, NotificationEventReceiver.class); intent.setAction(ACTION_DELETE_NOTIFICATION); return PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT); } }
Now let’s create an
IntentService
to actually create notifications.There, we specify
onHandleIntent()
which is responses on NotificationEventReceiver‘s intent we passed instartWakefulService
method.If it’s Delete action – we can log it to our analytics, for example. If it’s Start notification intent – then by using
NotificationCompat.Builder
we’re composing new notification and showing it byNotificationManager.notify
. While composing notification, we are also setting pending intents for click and remove actions. Fairly Easy.NotificationIntentService.java
public class NotificationIntentService extends IntentService { private static final int NOTIFICATION_ID = 1; private static final String ACTION_START = "ACTION_START"; private static final String ACTION_DELETE = "ACTION_DELETE"; public NotificationIntentService() { super(NotificationIntentService.class.getSimpleName()); } public static Intent createIntentStartNotificationService(Context context) { Intent intent = new Intent(context, NotificationIntentService.class); intent.setAction(ACTION_START); return intent; } public static Intent createIntentDeleteNotification(Context context) { Intent intent = new Intent(context, NotificationIntentService.class); intent.setAction(ACTION_DELETE); return intent; } @Override protected void onHandleIntent(Intent intent) { Log.d(getClass().getSimpleName(), "onHandleIntent, started handling a notification event"); try { String action = intent.getAction(); if (ACTION_START.equals(action)) { processStartNotification(); } if (ACTION_DELETE.equals(action)) { processDeleteNotification(intent); } } finally { WakefulBroadcastReceiver.completeWakefulIntent(intent); } } private void processDeleteNotification(Intent intent) { // Log something? } private void processStartNotification() { // Do something. For example, fetch fresh data from backend to create a rich notification? final NotificationCompat.Builder builder = new NotificationCompat.Builder(this); builder.setContentTitle("Scheduled Notification") .setAutoCancel(true) .setColor(getResources().getColor(R.color.colorAccent)) .setContentText("This notification has been triggered by Notification Service") .setSmallIcon(R.drawable.notification_icon); PendingIntent pendingIntent = PendingIntent.getActivity(this, NOTIFICATION_ID, new Intent(this, NotificationActivity.class), PendingIntent.FLAG_UPDATE_CURRENT); builder.setContentIntent(pendingIntent); builder.setDeleteIntent(NotificationEventReceiver.getDeleteIntent(this)); final NotificationManager manager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE); manager.notify(NOTIFICATION_ID, builder.build()); } }
Almost done. Now I also add broadcast receiver for BOOT_COMPLETED, TIMEZONE_CHANGED, and TIME_SET events to re-setup my AlarmManager, once device has been rebooted or timezone has changed (For example, user flown from USA to Europe and you don’t want notification to pop up in the middle of the night, but was sticky to the local time 🙂 ).
NotificationServiceStarterReceiver.java
public final class NotificationServiceStarterReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { NotificationEventReceiver.setupAlarm(context); } }
We need to also register all our services, broadcast receivers in AndroidManifest:
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="klogi.com.notificationbyschedule"> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" /> <uses-permission android:name="android.permission.WAKE_LOCK" /> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <service android:name=".notifications.NotificationIntentService" android:enabled="true" android:exported="false" /> <receiver android:name=".broadcast_receivers.NotificationEventReceiver" /> <receiver android:name=".broadcast_receivers.NotificationServiceStarterReceiver"> <intent-filter> <action android:name="android.intent.action.BOOT_COMPLETED" /> <action android:name="android.intent.action.TIMEZONE_CHANGED" /> <action android:name="android.intent.action.TIME_SET" /> </intent-filter> </receiver> <activity android:name=".NotificationActivity" android:label="@string/title_activity_notification" android:theme="@style/AppTheme.NoActionBar"/> </application> </manifest>
That’s it!
The source code for this project you can find here. I hope, you will find this post helpful.