Android - Display notification when application is in background

Question

I am using AlarmManager to periodically check for new content at some endpoint, validate if the results coming from the endpoint are the same as the ones I already have on my app, and if its not the same create a notification for each item.

What i need to know is how should i make the alarms to start only when the application is paused or stopped and cancel the alarms when de application is started or resumed.

where should i start the alarms and where should i cancel them?

In Android Notifications Guideline it says (on chapter: When not to display a notification):

Don't create a notification if the relevant new information is currently on screen. Instead, use the UI of the application itself to notify the user of new information directly in context. For instance, a chat application should not create system notifications while the user is actively chatting with another user.

If I have the application open i just want to disable alarms, when the application is closed/paused i want to cancel everything.

Answer 1

You need to create a Custom Application with global state and implement your own onPause and onResume at Application Level.

Create your own subclass of Application like this:

public class MyApplication extends Application {

    private static MyApplication sInstance;

    public MyApplication getInstance(){
        return sInstance;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        sInstance = this;
    }

    public void onStart() {
        // TODO: Stop your notification.
    }

    public void onStop() {
        // TODO: Start your notification.
    }

}

Specify its name in your AndroidManifest.xml's tag:

<application
    android:icon="@drawable/icon"
    android:label="@string/app_name"
    android:name="MyApplication">

Create a class to hold the counts of activities:

public class ActiveActivitiesTracker {

    private static int sActiveActivities = 0;

    public static void activityStarted()
    {
        if (sActiveActivities == 0) {
            // TODO: Here is presumably "application level" resume
            MyApplication.getInstance().onStart();
        }
        sActiveActivities++;
    }

    public static void activityStopped()
    {
        sActiveActivities--;
        if (sActiveActivities == 0) {
            // TODO: Here is presumably "application level" pause
            MyApplication.getInstance().onStop();
        }
    }
}

Then create a base activity (or do that in every activity), simply call the activityStarted() and activityStopped() methods:

@Override
public void onStart() {
    super.onStart();
    ActiveActivitiesTracker.activityStarted();
}

@Override
public void onStop() {
    super.onStop();
    ActiveActivitiesTracker.activityStopped();
}

For more details about Custom Application, see this.

For more details about Android Application Level Pause and Resume, see this.

Hope this helps.