Non-static variable cannot be referenced from a static context?

i'm a n00b in Android Coding, today I wanna try to use the location service.

I set up a simple class and a simple main, just to have longitude and latitude.

But when I try to call the construction for retrive the long and latitude Android Studio pop out the error:

"Error:(33, 16) error: non-static variable latitude cannot be referenced from a static context"

This is my location Class

public class AppLocationManager implements LocationListener {

    private LocationManager locationManager;
    private String latitude;
    private String longitude;
    private Criteria criteria;
    private String provider;

    public AppLocationManager(Context context) {
        locationManager = (LocationManager) context
                .getSystemService(Context.LOCATION_SERVICE);
        criteria = new Criteria();
        criteria.setAccuracy(Criteria.ACCURACY_FINE);
        provider = locationManager.getBestProvider(criteria, true);
        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,1,0,this);
        setMostRecentLocation(locationManager.getLastKnownLocation(provider));
    }

    private void setMostRecentLocation(Location lastKnownLocation) {

    }

    public String getLatitude() {
        return latitude;
    }

    public String getLongitude() {
        return longitude;
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * android.location.LocationListener#onLocationChanged(android.location.
     * Location)
     */
    @Override
    public void onLocationChanged(Location location) {
        double lon = (double) (location.getLongitude());/// * 1E6);
        double lat = (double) (location.getLatitude());// * 1E6);

//      int lontitue = (int) lon;
//      int latitute = (int) lat;
        latitude = lat + "";
        longitude = lon + "";

    }

    /*
     * (non-Javadoc)
     *
     * @see
     * android.location.LocationListener#onProviderDisabled(java.lang.String)
     */
    @Override
    public void onProviderDisabled(String arg0) {
        // TODO Auto-generated method stub

    }

    /*
     * (non-Javadoc)
     *
     * @see
     * android.location.LocationListener#onProviderEnabled(java.lang.String)
     */
    @Override
    public void onProviderEnabled(String arg0) {
        // TODO Auto-generated method stub

    }

    /*
     * (non-Javadoc)
     *
     * @see android.location.LocationListener#onStatusChanged(java.lang.String,
     * int, android.os.Bundle)
     */
    @Override
    public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
        // TODO Auto-generated method stub

    }

}