位置更新提供用于计算距离的随机数

Question

I'm currently trying to develop a running tracker on Android Studio, and I'm using a normal technique to get the distance and then turning it into miles rather than meters and I'm doing it inside of a service. However, it starts spurting out random long numbers when I start the emulated route. I know its to do with how I'm calculating the distance using distanceTo(), but no clue how to fix it. Not posting the entire code, but the relevant parts are blow

    @Override
    public void onCreate() {
        super.onCreate();
        Log.d("G53", "onCreate called");
        locationListener = new MyLocationListener();
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        try {
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 5, 5, locationListener);
            location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            oldLocation = location;

        } catch (SecurityException e) {
            Log.d("g53mdp", e.toString());
        }
    }

 public double getDistance() {

        if(running) {
            distance = distance * 0.000621371192;
            Log.d("tag", " " + distance);
            return distance;
        }
        return 0;

    }

    public void startExercise() {
        Log.d("tag", "startExercise called");
        startTime = System.currentTimeMillis();
        stopTime = 0;
        running = true;
        distance = 0;
    }

    public void stopExercise() {
        Log.d("tag", "stopExercise called");
        running = false;
        startTime = 0;
    }

    public class MyLocationListener extends Binder implements LocationListener, IInterface {

        @Override
        public void onLocationChanged(Location location) {
        
            if(running) {
                distanceInMetres = oldLocation.distanceTo(location);
                if (distanceInMetres < 10) {
                    Log.i("DISTANCE", "Values too close, so not used.");
                } else {
                    distance += distanceInMetres;
                    oldLocation = location;
                }
            }
        }

The output in Logcat looks like this

Answer 1

I have 2 thoughts.

I read your code, and your conversion for miles into meters is ok.

1.- I think the problem is you're reutilizing the distance variable in 2 or many methods, creating the overflow.

You are adding a distance here.

 distance += distanceInMetres;

That is perfect, but then you read that variable and assign them a new value in

public double getDistance() {

        if(running) {
            distance = distance * 0.000621371192;
            Log.d("tag", " " + distance);
            return distance;
        }
        return 0;

    }

So I suggest you change getDistance() into

public double getDistance() {
        if(running) {
            return distance * 0.000621371192;
        }
        return 0;
    }

And in that way, you no reassign values.

2.- Another possible issue could be a concurrence issue, but you need to post more about your code to follow.