Question

I am writing an Android application that requires the user’s current location. I register for location updates both from the network, and from GPS using the following code (locationManager is already defined):

    // Register the listener with the Location Manager to receive location updates.
    locationManager.requestLocationUpdates(
            LocationManager.NETWORK_PROVIDER,
            getResources().getInteger(R.integer.gps_min_time),
            getResources().getInteger(R.integer.gps_min_dist), this);
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
            getResources().getInteger(R.integer.gps_min_time),
            getResources().getInteger(R.integer.gps_min_dist), this);

I currently have this code in onCreate, but in order to save power, I remove both listeners in onPause and add them both again in onResume.

When the application starts, it adds both listeners twice, once in onCreate, and once in onResume. I have two question about this:

1. Does having each listener added twice mean that it actually gets added twice, or does the second call have no effect?
2. Should I remove the requestLocationUpdates from onCreate and just have them in onResume or should I remove all listeners first in onResume before adding them again?

Answer 1

1. your Listener will be added as a key to a Hashmap. So If you insert this (Your Activity) and don’t override equals it should be overridden, and has no effect, because it is the SAME Listener.

2. Anyway, I would remove the register inside onCreate and just leave it inside onResume, as you will save at least the time to Hash your listener and the Method calls.