Android location always null

2019-08-03 06:21发布

问题:

I had my application to find location working, but I changed some code and now the location always returns null. Ashamedly I am not sure what code I had changed, but I just cant seem to get it working.

Can anyone see why this returns null? I have been working on this all day with no joy. code below:

....imports....

public class Clue extends Activity {

public static double latitude;
public static double longitude;
Criteria criteria;
LocationManager lm;
LocationListener ll;
Location location;

  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
  setContentView(R.layout.questions);

  criteria = new Criteria();
  criteria.setAccuracy(Criteria.ACCURACY_FINE);
  lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
  ll = new MyLocationListener();
  lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, ll);

areWeThereYet();
}

   private void areWeThereYet()
  {
      if(weAreThere())
      {
      showMsgBox("There");  
    }
  else if(location!=null)
      toastMsg("not there");
       }

    private boolean weAreThere() {

location = getLocation(); 
if (location!=null)
{
longitude = location.getLongitude();
latitude = location.getLatitude();
return inCorrectPlace(question);
}
else
{
    toastMsg("Location not ready yet");
    return false;
}
}

private Location getLocation() {
     lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, ll);
      return lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
}

}

public class MyLocationListener implements LocationListener
{
    public void onLocationChanged(Location loc)
    {        
         Clue.longitude = loc.getLongitude();
         Clue.latitude = loc.getLatitude();
    }
}

I have added all permissions and simplified my code so you can all see what's going on.

Thanks,

Ben

回答1:

It's null because when you first start your activity in onCreate it isn't ready yet. When you eventually get the location update via onLocationChanged, you set the lat/lon on your Clue class but that's it... nothing re-calls your areWeThereYet method. You'd need to call that method after updating your location.