Start map with current location

I want the map in this application to start with the current location of the user but it keeps starting with the default location being the location with latitude = 0 and longitude = 0.

It also doesn't work when I walk around with phone in hand..

This is my code:

import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.location.LocationListener;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapsActivity extends FragmentActivity implements LocationListener {

    private GoogleMap mMap; // Might be null if Google Play services APK is not available.
    private LocationManager locationManager;
    private double longitude;
    private double latitude;
    public Criteria criteria;
    public String bestProvider;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);

        getLocation();

        setUpMapIfNeeded();
    }

    @Override
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
    }

    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (mMap == null) {
            // Try to obtain the map from the SupportMapFragment.
            mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                    .getMap();

            // Check if we were successful in obtaining the map.
            if (mMap != null) {
                setUpMap();
            }
        }
    }

    protected void getLocation() {

            locationManager = (LocationManager)  this.getSystemService(Context.LOCATION_SERVICE);
            criteria = new Criteria();
            bestProvider = String.valueOf(locationManager.getBestProvider(criteria, true)).toString();

            //You can still do this if you like, you might get lucky:
            Location location = locationManager.getLastKnownLocation(bestProvider);
            if (location != null) {
                Log.e("TAG", "GPS is on");
                latitude = location.getLatitude();
                longitude = location.getLongitude();
            }
            else{
                //This is what you need:
                locationManager.requestLocationUpdates(bestProvider, 1000, 0, this);
            }
    }

    private void setUpMap() {
        mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("My Location"));
    }

    @Override
    public void onLocationChanged(Location location) {
        //remove location callback:
        locationManager.removeUpdates(this);

        //open the map:
        latitude = location.getLatitude();
        longitude = location.getLongitude();
    }
// ... other LocationListener methods that I left empty. I removed to shorten the code
    }
}

Could you please tell me where's the problem? I've tried many fixes from StackOF but I couldn't get it to work.