Question

我试图从asynctask中获取用户的当前位置。我的应用程序取决于纬度和经度值。我试图向用户显示ProgressDialog，直到获取该位置。

问题： - 位置值始终为null。我知道获取GPS位置需要时间。但即使有时等待，我的位置值也为空。它总是空的。

以下是我的代码： -

   public class MainActivity extends ActionBarActivity {

            @Override
            protected void onCreate(Bundle savedInstanceState)
            {
                         super.onCreate(savedInstanceState);
                             setContentView(R.layout.activity_main);

                     //some action …

            }

            @Override
                public boolean onOptionsItemSelected(MenuItem item) 

                {

                     if (id == R.id.action_settings)
                     {
                        return true;
                     }

                     if(id == R.id.action_location)
                     {
                          LocationTask locGetter = new LocationTask(MainActivity.this);
                          locGetter.execute();
                     }
                     return super.onOptionsItemSelected(item);
        }
}

下面是我的AsyncTask

        public class LocationTask extends AsyncTask<Void,Void,Void> implements LocationListener
        {
                private ProgressDialog dialog;
                private Activity callingActivity;
                LocationManager locationManager;

             String provider = LocationManager.GPS_PROVIDER;

              public LocationTask(Activity activity)
                 {
                        callingActivity = activity;
                 }

                @Override
                protected void onPreExecute() 
                {
                    dialog= ProgressDialog.show(callingActivity,"Getting Co-ordinates","Please Wait....");
               }    

                @Override
                protected Void doInBackground(Void... voids) 
               {
                      locationManager = (LocationManager) callingActivity.getSystemService(Context.LOCATION_SERVICE);
                      Location location = locationManager.getLastKnownLocation(provider);
                      showLocation(location);
                          return null;
               }

                private void showLocation(Location location) 
               {

                    if(location == null)
                        {
                            Log.d("Location","Failed to get location");
                        }

                        else
                        {
                            Log.d("Location","Latitude :- "+location.getLatitude()+" Longitude :- "+location.getLongitude());
                        }
                }

                @Override
                protected void onPostExecute(Void aVoid)
                {
                        dialog.dismiss();
                        super.onPostExecute(aVoid);

                }

            @Override
            public void onLocationChanged(Location location) 
               {
                    showLocation(location);
               }    

            @Override
            public void onStatusChanged(String s, int i, Bundle bundle) {

            }

            @Override
            public void onProviderEnabled(String s) {

            }

            @Override
            public void onProviderDisabled(String s) {

            }
}

更新： -

正如Ivan所说，我修改了我的AsyncTask以获得如下位置： -

@Override
protected Void doInBackground(Void... voids) {
        locationManager = (LocationManager) callingActivity.getSystemService(Context.LOCATION_SERVICE);
        locationManager.requestLocationUpdates(provider,0,0,this);
        if(locationManager != null) {
            Location location = locationManager.getLastKnownLocation(provider);
            showLocation(location);
        }
return null;
}

但是这个抛出的窗户泄露了＃34; onPrexecute（）方法中dialog= ProgressDialog.show(callingActivity,"Getting Co-ordinates","Please Wait....");内的异常。

Answer 1

在我看来，您可能错过了requestLocationUpdates(...)来电。

请检查此related question以便更好地了解可能遗漏的内容，因为它确实不会出现在AsyncTask内部的问题，尽管我并不是真的看到需要在您的代码段中使用AsyncTask。

Android GPS位置在AsyncTask中始终为null

1 个答案: