Oreo Scheduling a Notification in an hour

Question

In Android Oreo, I'm trying to schedule notifications at known future times. I wrote a small piece of code to test if I can schedule a notification in an hour when the app might be closed. When I try to do this, nothing happens. I really appreciate the help.

public class MainActivity extends AppCompatActivity {
private NotificationManager manager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    NotificationChannel notificationChannel = new NotificationChannel("default",
            "primary", NotificationManager.IMPORTANCE_DEFAULT);
    manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    manager.createNotificationChannel(notificationChannel);
    Intent notifyIntent = new Intent(this, MyReceiver.class);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 1, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);
    AlarmManager alarmManager = (AlarmManager) this.getSystemService(Context.ALARM_SERVICE);
    long milisInFuture = 1000 * 60 * 60;
    alarmManager.set(AlarmManager.RTC_WAKEUP, milisInFuture, pendingIntent);
}

public class MyNewIntentService extends JobIntentService {
    @Override
    protected void onHandleWork(@NonNull Intent intent) {
        Notification notification = new Notification.Builder(getApplicationContext(), "default")
                .setContentTitle("title")
                .setContentText("body")
                .setSmallIcon(android.R.drawable.stat_notify_chat)
                .setAutoCancel(true)
                .build();
        manager.notify(123, notification);
    }
}

public class MyReceiver extends BroadcastReceiver {
    public MyReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        Intent intent1 = new Intent(context, MyNewIntentService.class);
        context.startService(intent1);
    }
}
}

Here is the manifest if that helps.

<?xml version="1.0" encoding="utf-8"?>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    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=".MainActivity$MyNewIntentService"
        android:permission="android.permission.BIND_JOB_SERVICE"></service>
</application>
</manifest>

Answer 1

UPDATE:

Don't forget to add the receiver in the manifest xml file. For this question:

Add in AndroidManifest.xml inside application tag:

<receiver android:name=".MyReceiver" />

Example: I am keeping this example, it updates the notification from Broadcast Receiver class.

Create a broadcast receiver class as shown, (Don't forget to add the receiver in the manifest xml file)

public class NotificationUpdate extends BroadcastReceiver {
    @RequiresApi(api = Build.VERSION_CODES.O)
    @Override
    public void onReceive(Context context, Intent intent) {
        //NEED A RESCHEDULE?
        updateNotification(context);
    }

    @RequiresApi(api = Build.VERSION_CODES.O)
    private void updateNotification(Context context){
        Notification notification = new Notification.Builder(context.getApplicationContext(), "default")
                .setContentTitle("title")
                .setContentText("body")
                .setSmallIcon(android.R.drawable.stat_notify_chat)
                .setAutoCancel(true)
                .build();
        NotificationManager manager=(NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
        if(manager!=null) manager.notify(123, notification);
    }
}

Example Call from an Activity:

public class MainActivity extends AppCompatActivity {

    final long intervalPeriod=60*1000;
    AlarmManager mAlarmManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        NotificationChannel notificationChannel = null;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            notificationChannel = new NotificationChannel("default",
                    "primary", NotificationManager.IMPORTANCE_DEFAULT);

            NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
            if (manager != null) manager.createNotificationChannel(notificationChannel);

            mAlarmManager=(AlarmManager)getApplicationContext().getSystemService(ALARM_SERVICE);
            PendingIntent intent=PendingIntent.getBroadcast(getApplicationContext(),1234,
                    new Intent(getApplicationContext(),NotificationUpdate.class),0);

            mAlarmManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, System.currentTimeMillis()+intervalPeriod, intent);

        }
    }