Loppers Android Error

Question

Hello i have one class in android

public class GPSTracker extends Service implements LocationListener {

    private final Context mContext;

    // flag for GPS status
    boolean isGPSEnabled = false;

    // flag for network status
    boolean isNetworkEnabled = false;

    // flag for GPS status
    boolean canGetLocation = false;

    Location location; // location
    double latitude; // latitude
    double longitude; // longitude

    // The minimum distance to change Updates in meters
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 5; // 10 meters

    // The minimum time between updates in milliseconds
    private static final long MIN_TIME_BW_UPDATES = 1000 * 30 * 1; // 1 minute

    // Declaring a Location Manager
    protected LocationManager locationManager;

    public GPSTracker(Context context) {
        this.mContext = context;
        getLocation();
    }

    public Location getLocation() {

        try {
            locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);

            // getting GPS status
            isGPSEnabled = locationManager
                    .isProviderEnabled(LocationManager.GPS_PROVIDER);

            // getting network status
            isNetworkEnabled = locationManager
                    .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

            if (!isGPSEnabled && !isNetworkEnabled) {
                // No est� activado el gps
                showSettingsAlert();
            } else {
                this.canGetLocation = true;
                if (isNetworkEnabled) {
                    locationManager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("Network", "Network");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
                // if GPS Enabled get lat/long using GPS Services
                if (isGPSEnabled) {
                    if (location == null) {
                        locationManager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER,
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                        Log.d("GPS Enabled", "GPS Enabled");
                        if (locationManager != null) {
                            location = locationManager
                                    .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            if (location != null) {
                                latitude = location.getLatitude();
                                longitude = location.getLongitude();
                            }
                        }
                    }
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return location;
    }

    /**
     * Stop using GPS listener
     * Calling this function will stop using GPS in your app
     * */
    public void stopUsingGPS(){
        if(locationManager != null){
            locationManager.removeUpdates(GPSTracker.this);
        }       
    }

    //Function to get latitude
    public double getLatitude(){
        if(location != null){
            latitude = location.getLatitude();
        }

        // return latitude
        return latitude;
    }

    //Function to get longitude
    public double getLongitude(){
        if(location != null){
            longitude = location.getLongitude();
        }

        // return longitude
        return longitude;
    }

    /**
     * Function to check GPS/wifi enabled
     * @return boolean
     * */
    public boolean canGetLocation() {
        return this.canGetLocation;
    }

    /**
     * Function to show settings alert dialog
     * On pressing Settings button will lauch Settings Options
     * */

    public void showSettingsAlert(){

        new AlertDialog.Builder(mContext)
        //.setIcon(android.R.drawable.ic_dialog_alert)
        .setTitle("Activar GPS")
        .setMessage("El GPS no esta habilitado. �Desea Activarlo?")
        .setPositiveButton("Si", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {

                Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                mContext.startActivity(intent);    
            }

        })
        .setNegativeButton("No", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {

                //TO DO   
            }

        } )
        .show();

    }

    @Override
    public void onLocationChanged(Location location) {
        this.location = location;
    }

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

    @Override
    public void onProviderEnabled(String provider) {
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
        // Setting Dialog Title
        alertDialog.setTitle("Activar GPS");
        // Setting Dialog Message
        alertDialog.setMessage("El GPS esta habilitado.");
        // Showing Alert Message
       // alertDialog.show();
    }
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {

    }
    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

}

its work and return gps but when im call in another class im send error for lopper.prepare

java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

getLocation(GPSTracker.java:69)

(GPSTracker.java:47)

where have a error?

regards!

Answer 1

I think the solution is simple. Why do you extend Service. I have seen many implementations of GPSTracker, have used one myself too and there is no need to extend any class. Just get rid of the "extends Service" part and all methods that come from extending service and you will be OK. Whenever you need location data create a GPSTracker object.

If you want to get notified when the tracker gets the data than just create an interface and implement it in the Activity. After that do this:

listener.onInterfaceMethod(location);