1. Location

2. GPS Global Positioning System – At least 4 satellites typically used 3 required extra for error detection and altitude typically accurate within 20 ft high power consumption requires line of sight to satellites – trilateration intersection of spheres indicating distance from satellites

3. Other Location Based Services (LBS) Network – Typically associated with mobile networks – Towers are used in place of satellites not as accurate as GPS – typically within 200 ft does not consume as much power Passive – WIFI extremely fast, no additional power usage lower accuracy – typically within 1 mile Google maintains a location database and uses wifi signal to determine location

4. Components of Location in Android Permissions within Manifest file LocationManager class Location class LocationListener interface

5. Permissions within Manifest file

6. Permissions uses-permission tags – children of manifest tag – often placed above application tag allows access to GPS, network, or passive only allows access to network

7. LocationManager class

8. LocationManager Concrete class Gives access to LBS services and classes Not instantiated directly – instantiated through the given context’s getSystemService() method LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

9. LocationManager important methods – getLastKnownLocation argument: desired provider – getBestProvider arguments – Criteria to use (power requirement, accuracy, bearing, speed, altitude) » usually a default Criteria object – boolean value » true – only those available and accessible (and meet criteria) » false – all providers on device (and meet criteria) returns String indicating the best provider – getProviders returns List of all providers, with same boolean argument as getBestProvider (no criteria argument) – getAllProviders returns List of all providers (no arguments)

10. Sample code Code to obtain current location LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE); String bestProvider = lm.getBestProvider(new Criteria(), true); Location l = lm.getLastKnownLocation(bestProvider);

11. Sample code LocationManager – methods associated with Listener – Registering a listener arguments – provider to use – minimal time interval in milliseconds – minimal distance changed in meters – LocationListener examples – lm.requestLocationUpdates(lm.getBestProvider(new Criteria(), true), 1000, 1000, this); – lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 1000, 1000, this); – Unregistering a listener lm.removeUpdates(this);

12. Location class

13. Concrete class Represents geographic location Types of data in this class: – accuracy – in meters – altitude – in meters – bearing – degrees east of true north – latitude – longitude – provider – speed – m/s – timestamp – ms since 1/1/1970

14. Location class important methods – getters for data getAltitude() getAccuracy() etc.

15. Sample code – Using current location LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE); String bestProvider = lm.getBestProvider(new Criteria(), true); Location myLocation = lm.getLastKnownLocation(bestProvider); if (myLocation != null) { tvLatitude.setText(String.valueOf(myLocation.getLatitude())); …other code using the location goes here } else { …code handling inability to retrieve a location goes here }

16. LocationListener interface

17. LocationListener Interface Notified by LocationManager if status changes LocationManager must register with the LocationListener

18. LocationListener 4 abstract methods – onLocationChanged parameter is the new location – onProviderDisabled and onProviderEnabled parameter is the provider (String) – onStatusChanged 3 parameters – provider (String) – status of provider (int) – constants from LocationProvider class » OUT_OF_SERVICE » TEMPORARILY_UNAVAILABLE » AVAILABLE – extras (Bundle) – currently the number of satellites

19. LocationListener Registering/Unregistering a Manager with a Listener – methods in LocationManager class Register – requestLocationUpdates(provider, delay, distance, listener) » provider (String) » delay between updates (int in ms) » distance (float indicating minimum distance change before update) » listener – the LocationListener Unregister – removeUpdates(provider) – take care to utilize resources effectively register in onResume() unregister in onPause()

20. Typical Approach The main GPS Activity extends Activity and implements LocationListener – within this activity: 4 abstract methods from LocationListener are implemented LocationManager and Location classes are used as needed Handle the case where the Location is null onResume and onPause methods are used to handle registering and unregistering the LocationListener – other Activities are used as needed

21. Simulating locations in emulator DDMS (Dalvik Debug Monitor Service) – Perspective in Eclipse – Many views associated with it to monitor Android Screen capture Monitoring memory usage Logcat Mock data, calls, location Other – In DDMS perspective, mock locations can be set in the Emulator Control view manually enter longitude and latitude upload.gpx or.kml files