How do I update the notification text for a foreground service in Android?

When you want to update a Notification set by startForeground(), simply build a new notication and then use NotificationManager to notify it.

The key point is to use the same notification id.

I didn’t test the scenario of repeatedly calling startForeground() to update the Notification, but I think that using NotificationManager.notify would be better.

Updating the Notification will NOT remove the Service from the foreground status (this can be done only by calling stopForground );

Example:

private static final int NOTIF_ID=1;

@Override
public void onCreate (){
    this.startForeground();
}

private void startForeground() {
    startForeground(NOTIF_ID, getMyActivityNotification(""));
}

private Notification getMyActivityNotification(String text){
    // The PendingIntent to launch our activity if the user selects
    // this notification
    CharSequence title = getText(R.string.title_activity);
    PendingIntent contentIntent = PendingIntent.getActivity(this,
            0, new Intent(this, MyActivity.class), 0);

    return new Notification.Builder(this)
            .setContentTitle(title)
            .setContentText(text)
            .setSmallIcon(R.drawable.ic_launcher_b3)
            .setContentIntent(contentIntent).getNotification();     
}

/**
 * This is the method that can be called to update the Notification
 */
private void updateNotification() {
    String text = "Some text that will update the notification";

    Notification notification = getMyActivityNotification(text);

    NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    mNotificationManager.notify(NOTIF_ID, notification);
}

The documentation states

To set up a notification so it can be updated, issue it with a
notification ID by calling NotificationManager.notify(). To update
this notification after you’ve issued it, update or create a
NotificationCompat.Builder object, build a Notification object from
it, and issue the Notification with the same ID you used previously.
If the previous notification is still visible, the system updates it
from the contents of the Notification object. If the previous
notification has been dismissed, a new notification is created
instead.