Location Based Services (LBS) on Android :

Location and maps-based applications are compelling for mobile device users.

You can build application by android.location packages and com.google.android.maps.MapView which is sub class of ViewGroup in Andorid.

Location Services :

1.Android gives your applications access to the location services supported by the device through the classes in the android.location package.

2.The central component of the location framework is the LocationManager system service, which provides APIs to determine location and bearing of the underlying device (if available).

You do not instantiate a LocationManager directly. Rather, you request an instance from the system by calling getSystemService(Context.LOCATION_SERVICE). The method returns a handle to a new LocationManager instance.

Once your application has a LocationManager, your application is able to do three things:

1.we can Query for the list of all LocationProviders for the last known user location.

2.Register/unregister for periodic updates of the user's current location from a location provider .

3.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.

Next Post we will see this location services with Examples.

Location Manager Examples

Here theres is a small program regarding location manager and location class

package com.vinnysoft.ami;

import java.util.List;
import java.util.Locale;

import android.app.Activity;
import android.content.Context;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.TextView;

public class WhereAmI extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

LocationManager locationManager;
String context = Context.LOCATION_SERVICE;
locationManager = (LocationManager)getSystemService(context);

Criteria crta = new Criteria();
crta.setAccuracy(Criteria.ACCURACY_FINE);
crta.setAltitudeRequired(false);
crta.setBearingRequired(false);
crta.setCostAllowed(true);
crta.setPowerRequirement(Criteria.POWER_LOW);
String provider = locationManager.getBestProvider(crta, true);

// String provider = LocationManager.GPS_PROVIDER;
Location location = locationManager.getLastKnownLocation(provider);
updateWithNewLocation(location);

locationManager.requestLocationUpdates(provider, 1000, 0, locationListener);
}

private final LocationListener locationListener = new LocationListener()
{

@Override
public void onLocationChanged(Location location) {
updateWithNewLocation(location);
}

@Override
public void onProviderDisabled(String provider) {
updateWithNewLocation(null);
}

@Override
public void onProviderEnabled(String provider) {
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}

};
private void updateWithNewLocation(Location location) {
String latLong;
TextView myLocation;
myLocation = (TextView) findViewById(R.id.myLocation);

String addressString = "no address found";

if(location!=null) {
double lat = location.getLatitude();
double lon = location.getLongitude();
latLong = "Lat:" + lat + "\nLong:" + lon;

double lattitude = location.getLatitude();
double longitude = location.getLongitude();

Geocoder gc = new Geocoder(this,Locale.getDefault());
try {
List

addresses= gc.getFromLocation(lattitude, longitude, 1);
StringBuilder sb = new StringBuilder();
if(addresses.size()>0) {
Address address = addresses.get(0);
for(int i =0;i sb.append(address.getAddressLine(i)).append("\n");
sb.append(address.getLocality()).append("\n");
sb.append(address.getPostalCode()).append("\n");
sb.append(address.getCountryName());
}
addressString = sb.toString();
}
}catch (Exception e) {
}
} else {
latLong = " NO Location Found ";
}
myLocation.setText("your Current Position is :\n" +latLong + "\n " + addressString );
}
}


add mapview in main.xml file

give the permission sin android manifest file