Android - AlertDialog() crashes

Question

I'm getting this error when I'm running my project. I've searched and I think that the problem has something to do with the context, but I don't know how to solve it.

My code: (I think the error is in the method showSettingsAlert())

public class GPSTracker extends Service implements LocationListener {

private final Context mContext;

private TextView textView;


// 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 = 1000; // 1000 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 60000 * 60 * 1; // 60 minute

// Declaring a Location Manager
protected LocationManager locationManager;

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    getLocation();
    return START_STICKY;
}

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 network provider is enabled
        } else {
            this.canGetLocation = true;
            // First get location from Network Provider
            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();
    }
    stopUsingGPS();
    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(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);


    // Setting Dialog Title
    alertDialog.setTitle("GPS is settings");

    // Setting Dialog Message
    alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

    // On pressing Settings button
    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            mContext.startActivity(intent);
        }
    });

    // on pressing cancel button
    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });

    // Showing Alert Message
    alertDialog.show();
}

@Override
public void onLocationChanged(Location location) {
    textView.append("\n "+location.getLatitude()+" "+location.getLongitude());
}

@Override
public void onProviderDisabled(String provider) {
    Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
    mContext.startActivity(intent);
}

@Override
public void onProviderEnabled(String provider) {
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}

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

}

Here is my Logcat:

10-25 20:29:30.277 10524-10524/com.example.nunog.myapplication12 E/AndroidRuntime: FATAL EXCEPTION: main
                                                                               Process: com.example.nunog.myapplication12, PID: 10524
                                                                               java.lang.RuntimeException: Unable to start service com.example.nunog.myapplication12.Anomaly@424d1620 with Intent { cmp=com.example.nunog.myapplication12/.Anomaly (has extras) }: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
                                                                                   at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3006)
                                                                                   at android.app.ActivityThread.access$2200(ActivityThread.java:174)
                                                                                   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1404)
                                                                                   at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                   at android.os.Looper.loop(Looper.java:146)
                                                                                   at android.app.ActivityThread.main(ActivityThread.java:5593)
                                                                                   at java.lang.reflect.Method.invokeNative(Native Method)
                                                                                   at java.lang.reflect.Method.invoke(Method.java:515)
                                                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
                                                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
                                                                                   at dalvik.system.NativeStart.main(Native Method)
                                                                                Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
                                                                                   at android.view.ViewRootImpl.setView(ViewRootImpl.java:775)
                                                                                   at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:278)
                                                                                   at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
                                                                                   at android.app.Dialog.show(Dialog.java:301)
                                                                                   at android.app.AlertDialog$Builder.show(AlertDialog.java:957)
                                                                                   at com.example.nunog.myapplication12.GPSTracker.showSettingsAlert(GPSTracker.java:176)

EDIT: I've already try to use this instead of mContext in my AlertDialog(), but when I do that I get a NullPointerException.

The problem is you are trying to show an `AlertDialog` from a `Service`. The error you are getting is telling you the context you provided does not have a window token. You can only show an `AlertDialog` from an `Activity` context which has a window token. — Bobbake4, Oct 27 '16 at 14:27

score 0 · Answer 1 · edited May 23 '17 at 10:34

0

You can only create a Alert Dialog with an Activity like Bobbake4 has already commented.

An other answer maybe can help you: https://stackoverflow.com/a/22627480/2972104

edited May 23 '17 at 10:34

Community

1
1

answered Oct 28 '16 at 06:55

Bytehawks

271
4
11

score 0 · Answer 2 · answered Oct 28 '16 at 13:52

0

Create constructor of your class and pass the Context of Activity

private Context mContext;

public GPSTracker(Context context) {
        mContext = context;
}

Make object in your class like this

GPSTracker tracker = new GPSTracker(YourActivity.this);

answered Oct 28 '16 at 13:52

Multidots Solutions

591
4
14

Warrocker · Answer 3 · 2016-10-28T13:47:46.173

-2

Your mContext is null, use Activity to show alertDialog , not in Service, Service is a background task, it can't work with UI

edited Oct 28 '16 at 13:47

answered Oct 27 '16 at 14:31

Warrocker

734
6
12

Android - AlertDialog() crashes

3 Answers3