Building Map application in android

We can build Map application in Android  using
1 Classes of the android.location package
2 Google Maps external library.

 android.location package.--->The central component of the location framework is the LocationManager system service, which provides APIs to determine location

We do not instantiate a LocationManager directly. Rather, we request an instance from the system by calling getSystemService(Context.LOCATION_SERVICE). The method returns a handle to a new LocationManager instance.
Once our application has a LocationManager, our application is able to do three things:

• Query for the list of all LocationProviders for the last known user location.
• Register/unregister for periodic updates of the user's current location from a location provider (specified either by criteria or name).
• Register/unregister for a given Intent to be fired if the device comes within a given proximity (specified by radius in meters) of a given lat/long.

Google Maps External Library

Google provides a Maps external library that includes the com.google.android.maps package. The classes of the com.google.android.maps package offer built-in downloading, rendering, and caching of Maps tiles, as well as a variety of display options and controls.
The key class in the Maps package is com.google.android.maps.MapView, a subclass of ViewGroup. A MapView displays a map with data obtained from the Google Maps service.  It also provides all of the UI elements necessary for users to control the map. Our application can also use MapView class methods to control the MapView programmatically and draw a number of Overlay types on top of the map.
In general, the MapView class provides a wrapper around the Google Maps API that lets your application manipulate Google Maps data through class methods, and it lets you work with Maps data as you would other types of Views.
The Maps external library is not part of the standard Android library, so it may not be present on some compliant Android-powered devices. Similarly, the Maps external library is not included in the standard Android library provided in the SDK. So that you can develop using the classes of the com.google.android.maps package, the Maps external library is made available to you as part of the Google APIs add-on for the Android SDK.