Question

I have an Android application which depends on the value returned by a webservice. This value changes only once a week. Clients should detect this changed value, but the exact time they detect this change is not really important, 12 to 24 hours later should be no problem.

My current implementation starts an IntentService in the onCreate() method of my custom Application class which retrieves the value from the webservice. I also persist the last retrieved value in the SharedPreferences, so the application does not have to wait until this value is retrieved.

Now my question is if it is necessary to schedule the retrieval of this value after it’s first retrieval in the onCreate() method, lets say after 12 hours. I know the onCreate() method is called only once in the lifecycle of an application, but I do not know how likely it is an application will be terminated by the Android system. Is it reasonable to assume that the application will be terminated enough times so that scheduling is not necessary? And in the case I should schedule the operation, what will be the best way to achieve this?

Answer 1

If you used onCreate(), I don’t think you’d have any guarantees that it would be called a second time. E.g. if the user plugs their phone in to charge, has go-to-sleep turned off and leaves your app running for days on end. Very unlikely, but not impossible.

If I were you I’d set up some sort of scheduled task. Maybe this link will help:

http://developer.android.com/resources/articles/timed-ui-updates.html

The example uses an OnClickListener to cancel the task.

OnClickListener mStopListener = new OnClickListener() {
   public void onClick(View v) {
       mHandler.removeCallbacks(mUpdateTimeTask);
   }
};

You would want to put this elsewhere, in onDestroy() perhaps.