stopping location service

[michaeldebruin]

Hello all,
I am trying to write a location service which can run on an interval. But somehow when I press the stop button and call on the onDestroy method, it crashes. And I just can't figure out why.

package com.example.locationservice;
 
import java.util.Timer;
import java.util.TimerTask;
 
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.location.Criteria;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.widget.Toast;
 
public class Location extends Service {
 
    Handler handler = new Handler();
    Timer myTimer = null;
    LocationManager locMan;
    public static double latitude = 0;
    public static double longitude = 0;
    int sleepTime = 1000 * 5;
    LocationListener myLocListener;
 
    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }
 
    @Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();
 
        locMan = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
 
        if (!locMan.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
            Toast.makeText(getApplicationContext(),
                    "Please turn your GPS on and start the service again",
                    Toast.LENGTH_LONG).show();
            stopSelf();
        }
 
        if (myTimer != null) {
            myTimer.cancel();
        } else {
            myTimer = new Timer();
        }
 
        Toast.makeText(getApplicationContext(), "Service Started",
                Toast.LENGTH_LONG).show();
 
        myTimer.scheduleAtFixedRate(new LocationDisplayTask(), 0, sleepTime);
    }
 
    class LocationDisplayTask extends TimerTask {
 
        @Override
        public void run() {
            // TODO Auto-generated method stub
            handler.post(new Runnable() {
 
                @Override
                public void run() {
                    // TODO Auto-generated method stub
                    boolean go = false;
 
                    while (go) {
 
                        try {
                            int minTime = 0;
                            float minDistance = 0;
 
                            LocationListener myLocListener = new LocationListener() {
 
                                @Override
                                public void onStatusChanged(String provider,
                                        int status, Bundle extras) {
                                    // TODO Auto-generated method stub
 
                                }
 
                                @Override
                                public void onProviderEnabled(String provider) {
                                    // TODO Auto-generated method stub
 
                                }
 
                                @Override
                                public void onProviderDisabled(String provider) {
                                    // TODO Auto-generated method stub
 
                                }
 
                                @Override
                                public void onLocationChanged(
                                        android.location.Location location) {
                                    // TODO Auto-generated method stub
                                    String loc = "Latitude: "
                                            + location.getLatitude()
                                            + "Longitude: "
                                            + location.getLongitude();
 
                                    Toast.makeText(getApplicationContext(),
                                            loc, Toast.LENGTH_LONG).show();
                                }
                            };
                            locMan = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
 
                            Criteria criteria = new Criteria();
                            criteria.setPowerRequirement(Criteria.POWER_LOW);
                            criteria.setAccuracy(Criteria.ACCURACY_FINE);
                            criteria.setAltitudeRequired(false);
                            criteria.setBearingRequired(false);
                            criteria.setCostAllowed(true);
                            criteria.setSpeedRequired(false);
 
                            String BestProvider = locMan.getBestProvider(
                                    criteria, false);
 
                            locMan.requestLocationUpdates(BestProvider,
                                    minTime, minDistance, myLocListener);
 
                        } catch (Exception e) {
                            e.printStackTrace();
                            go = false;
                        }
                    }
                }
            });
        }
    }
 
    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        myTimer.cancel();
        locMan.removeUpdates(myLocListener);
        Toast.makeText(getApplicationContext(), "Service Stopped",
                Toast.LENGTH_SHORT).show();
    }
}

Any help will be high;y appreciated.

[r035198x]

Does it crash with an error message or stack trace?

[michaeldebruin]

The screen just freezes, then turns black. And then it says that the application has stopped working.

[r035198x]

Try running it in debug mode and checking the logs or debugging in the simulator.

[adri00713]

i have a question

Given the list of a maximum of 10 numbers, where all numbers
are different in the list create a method that will
return all possible combinations in each combination the
of the numbers should be equal to 10.

example: input number list {0,2,3,5,10}

output is

{2,3,5} {0,10}

[michaeldebruin]

@r035198x, I did that and it seems that this line of code:

locMan.removeUpdates(myLocListener);

caused an argumentNullexception. So I've made an if statement which checks whether the listener is null or not. But it still causes the error. Do you have any idea what is going wrong?

[r035198x]

You have two different myLocListener; variables declared.
One at near the top

LocationListener myLocListener;

and the other inside the thread

LocationListener myLocListener = new LocationListener() {

The one outside the thread is never initialized.

[michaeldebruin]

I've solved my problem. Surrounded the whole retrieve location part with a while loop. And then just interrupted the loop.

[r035198x]

Ok, you should still not be hiding that myLocListener variable though so you should fix that if it's still there.

[michaeldebruin]

no it ain't there anymore. So fixed that one too.