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

My code: (i think the error it's on 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;

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 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)
Nuno Pardal
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2 Answers2

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Make sure you are using Context of Activity not of Application class. For more detail if needed between Activity and Application context, please refer- https://stackoverflow.com/a/35189629/1380032

Community
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Rahul
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0

Try to use this as a Context instead of mContext because Service is a Context. also, you should call the getLocation() Method from onCreate() or onStartCommand(). There is already a Constructor in the Service class and you shouldn't override the Constructor.

T.S
  • 911
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  • I try that and now i get a NullPointerException in "AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);" @T.S – Nuno Pardal Oct 26 '16 at 13:42