portfoliobuilder portfoliobuilder - 1 year ago 53
Android Question

Is it bad practice to getLastKnownLocation any time someone moves a pin on the map?

I have implemented GoogleMap.OnMyLocationChangeListener and attached to my map object OnMyLocationChangeListener so that whenever any movement is done on the map, I can receive feedback of these changes in the callback method

@Override
public void onMyLocationChange(android.location.Location location) {
}


I was reading the Android Developers strategies documentation (https://developer.android.com/guide/topics/location/strategies.html) and learned that there is a function to determine whether one location reading is better than the current location fix

What I decided to do was check for a better location with every map change. In order to do this, I am passing in the lastKnownGPSLocation and the location object from onMyLocationChange callback. From my knowledge, calling getLastKnownLocation can be expensive and battery draining. This is the idea of what I am doing.

if (isBetterLocation(mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER), location) {
// update my current lat/long
}


And the function for isBetterLocation() is the following:

/** Determines whether one Location reading is better than the current Location fix
* @param location The new Location that you want to evaluate
* @param currentBestLocation The current Location fix, to which you want to compare the new one
*/
protected boolean isBetterLocation(Location location, Location currentBestLocation) {
if (currentBestLocation == null) {
// A new location is always better than no location
return true;
}

// Check whether the new location fix is newer or older
long timeDelta = location.getTime() - currentBestLocation.getTime();
boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
boolean isNewer = timeDelta > 0;

// If it's been more than two minutes since the current location, use the new location
// because the user has likely moved
if (isSignificantlyNewer) {
return true;
// If the new location is more than two minutes older, it must be worse
} else if (isSignificantlyOlder) {
return false;
}

// Check whether the new location fix is more or less accurate
int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy());
boolean isLessAccurate = accuracyDelta > 0;
boolean isMoreAccurate = accuracyDelta < 0;
boolean isSignificantlyLessAccurate = accuracyDelta > 200;

// Check if the old and new location are from the same provider
boolean isFromSameProvider = isSameProvider(location.getProvider(),
currentBestLocation.getProvider());

// Determine location quality using a combination of timeliness and accuracy
if (isMoreAccurate) {
return true;
} else if (isNewer && !isLessAccurate) {
return true;
} else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
return true;
}
return false;
}

/** Checks whether two providers are the same */
private boolean isSameProvider(String provider1, String provider2) {
if (provider1 == null) {
return provider2 == null;
}
return provider1.equals(provider2);
}


Is this how this function is intended to be used? I have noticed that other people use this as a Service. Thanks in advance.

Answer Source

According to this documentation, in working with location data, the location data available to an Android device includes the current location of the device pinpointed using a combination of technologies. The direction and method of movement, and whether the device has moved across a predefined geographical boundary, or geofence. Then depending on the needs of your application, you can choose between these methods in working with location data.

  • The My Location layer provides a simple way to display a device's location on the map. It does not provide data.

  • The Google Play services Location API is recommended for all programmatic requests for location data.

  • The LocationSource interface allows you to provide a custom location provider.

Also, from this documentation, the Google Play services location APIs are now the preferred way in adding a location awareness in the app. Just read the documentation link above to know more information and sample code on how to achieve this.