Android™ Application Development - Bahar Ali Khan

Chapter 7: Maps, Geocoding, and Location-Based Services
Having defi ned the required Criteria, you can use getBestProvider to return the best matching
Location Provider or getProviders to return all the possible matches. The following snippet demonstrates
using getBestProvider to return the best provider for your criteria where the Boolean lets you
restrict the result to a currently enabled provider:
String bestProvider = locationManager.getBestProvider(criteria, true);
If more than one Location Provider matches your criteria, the one with the greatest accuracy is
returned. If no Location Providers meet your requirements, the criteria are loosened, in the following
order, until a provider is found:
❑
❑
❑
Power use
Accuracy
Ability to return bearing, speed, and altitude
The criterion for allowing a device with monetary cost is never implicitly relaxed. If no provider is
found, null is returned.
To see a list of names for all the providers that match your criteria, you can use getProviders. It accepts
Criteria and returns a fi ltered String list of all available Location Providers that match them. As with the
getBestProvider call, if no matching providers are found, this call returns null.
List matchingProviders = locationManager.getProviders(criteria,
false);
Finding Your Location
The purpose of location-based services is to fi nd the physical location of the device.
Access to the location-based services is handled using the Location Manager system Service. To access
the Location Manager, request an instance of the LOCATION_SERVICE using the getSystemService
method, as shown in the following snippet:
String serviceString = Context.LOCATION_SERVICE;
LocationManager locationManager;
locationManager = (LocationManager)getSystemService(serviceString);
Before you can use the Location Manager, you need to add one or more uses-permission tags to your
manifest to support access to the LBS hardware.
The following snippet shows the fi ne and coarse permissions. Of the default providers, the GPS provider
requires fi ne permission, while the Network provider requires only coarse. An application that has
been granted fi ne permission will have coarse permission granted implicitly.
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