Question

I have looked about and cannot find any direct threads regarding what I am looking for. I am trying to create an Android application which dials out an emergency number at the push of a button (which I have got working) but cannot get the location (displayed in Longitude and Latitude) to display, I have tried doing it with Toast and EditText boxes. I am new to Android development so wanted to start with something easy, but the LongLat part is being troublesome. Any help would be greatly appreciated.

Below is the code I have been tampering with in order to try and get it to grab the Long and Lat, then in another file I have been trying to use a click listener to assign it to a button so when the button is pressed (in main.xml) it will display the Long and Lat either in a textfield or in toast.

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



        public class EmergencyLocation extends Activity implements LocationListener {
            private TextView latituteField;
            private TextView longitudeField;
            private LocationManager locationManager;
            private String provider;

            /** Called when the activity is first created. **/
            @Override
            public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.main);
                latituteField = (TextView) findViewById(R.id.TextView);
                longitudeField = (TextView) findViewById(R.id.long_lat);

                // Get the location manager
                locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
                // Define the criteria how to select the location provider -> use
                // default
                Criteria criteria = new Criteria();
                provider = locationManager.getBestProvider(criteria, false);
                Location location = locationManager.getLastKnownLocation(provider);

                // Initialise the location fields
                if (location != null) {
                    System.out.println("Provider " + provider + " has been selected.");
                    int lat = (int) (location.getLatitude());
                    int lng = (int) (location.getLongitude());
                    latituteField.setText(String.valueOf(lat));
                    longitudeField.setText(String.valueOf(lng));
                } else {
                    latituteField.setText("Provider not available");
                    longitudeField.setText("Provider not available");
                }
            }








        private void TextView() {
            // TODO Auto-generated method stub

        }


        @Override
        public void onLocationChanged(Location arg0) {
            // TODO Auto-generated method stub

        }


        @Override
        public void onProviderDisabled(String arg0) {
            // TODO Auto-generated method stub

        }


        @Override
        public void onProviderEnabled(String arg0) {
            // TODO Auto-generated method stub

        }


        @Override
        public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
            // TODO Auto-generated method stub

        }} 

Answer 1

First, you need to set up a LocationManager:

LocationManager manager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);

// set preferred provider based on the best accuracy possible
Criteria fineAccuracyCriteria = new Criteria();
fineAccuracyCriteria.setAccuracy(Criteria.ACCURACY_FINE);
String preferredProvider = manager.getBestProvider(fineAccuracyCriteria, true);

Now, you have to create a LocationListener. In this case, it calls the method updateLocation():

LocationListener listener = new LocationListener() {
        public void onLocationChanged(Location location) {
            // called when a new location is found by the network location provider.
            updateLocation(location);
        }

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

        public void onProviderEnabled(String provider) {}

        public void onProviderDisabled(String provider) {}
    };

EDIT:

Then, you have to register the listener with your LocationManager (and try to get the cached location):

manager.requestLocationUpdates(preferredProvider, 0, 0, listener);
// get a fast fix - cached version
updateLocation(manager.getLastKnownLocation());

And finally, the updateLocation() method:

private void updateLocation(Location location) {
    if (location == null)
        return;

    // save location details
    latitude = (float) location.getLatitude();
    longitude = (float) location.getLongitude();        
}

EDIT2:

OK, just saw your code. In order to make it work, just move around a few bits:

/** Called when the activity is first created. **/
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    latituteField = (TextView) findViewById(R.id.TextView);
    longitudeField = (TextView) findViewById(R.id.long_lat);

    // Get the location manager
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    // Define the criteria how to select the location provider -> use
    // default
    Criteria criteria = new Criteria();
    provider = locationManager.getBestProvider(criteria, false);
    locationManager.requestLocationUpdates(provider, 0, 0, this);
    Location location = locationManager.getLastKnownLocation(provider);
    onLocationChanged(location);
}

@Override
protected void onDestroy() {
    super.onDestroy();
    locationManager.removeUpdates(this);
}

@Override
public void onLocationChanged(Location location) {
   if (location != null) {
       System.out.println("Provider " + provider + " has been selected.");
       int lat = (int) (location.getLatitude());
       int lng = (int) (location.getLongitude());
       latituteField.setText(String.valueOf(lat));
       longitudeField.setText(String.valueOf(lng));
   } else {
       latituteField.setText("Provider not available");
       longitudeField.setText("Provider not available");
   }
}

Hope it helps!