GPS location in android

First initialize   LocationManager,LocationListerner ,Location
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public class TestGPS extends Activity {

    private LocationManager locationmanager;
    private LocationListener locationlistener;
    private Location location;

    String lattitude, longitude;
   
    Button btn_captured;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        Button btn = (Button) findViewById(R.id.btn_gps);
       
        btn_captured = (Button) findViewById(R.id.btn_captured);

        locationmanager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

   
        locationmanager.requestLocationUpdates(locationmanager.GPS_PROVIDER, 0,
                0, new MyLocationListener());
        btn.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                setCurrentLocation();

            }
        });

    }

    protected void setCurrentLocation() {
        Location location = locationmanager
                .getLastKnownLocation(locationmanager.GPS_PROVIDER);
        if (location != null) {
            String message = String.format(
                    "Current Location \n Longitude: %1$s \n Latitude: %2$s",
                    location.getLongitude(), location.getLatitude());
            Toast.makeText(TestGPS.this, message, Toast.LENGTH_LONG)
                    .show();
            btn_captured.setVisibility(View.VISIBLE);
           
        }

    }
   
     private class MyLocationListener implements LocationListener {
           
                     public void onLocationChanged(Location location) {
                         String message = String.format(
                             "New Location \n Longitude: %1$s \n Latitude: %2$s",
                             location.getLongitude(), location.getLatitude()
                         );
                     Toast.makeText(AsdasdActivity.this, message, Toast.LENGTH_LONG).show();
                     }
            
                     public void onStatusChanged(String s, int i, Bundle b) {
                         Toast.makeText(TestGPS.this, "Provider status changed",
                             Toast.LENGTH_LONG).show();
                     }
         
                    public void onProviderDisabled(String s) {
                     Toast.makeText(TestGPS.this,
                             "Provider disabled by the user. GPS turned off",
                                 Toast.LENGTH_LONG).show();
                 }
           
                     public void onProviderEnabled(String s) {
                         Toast.makeText(TestGPS.this,
                                 "Provider enabled by the user. GPS turned on",
                            Toast.LENGTH_LONG).show();
                 }
            
                 }

}