未启用 GPS 时应用程序强制关闭

Question

我无法弄清楚为什么在未启用 GPS 时我的应用程序强制关闭。在运行前启用时，一切都很好。一切工作正常，直到我添加 LocationListener 来更新当前位置。我确信这件事简单得可笑。

 public class GlenrochieMain extends Activity

 {


   @Override

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);     
        setContentView(R.layout.main);      

    //GPS Functionality

    LocationManager locationManager;
    String context = Context.LOCATION_SERVICE;
    locationManager = (LocationManager)getSystemService(context);

    //Criteria for GPS
    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);
    criteria.setAltitudeRequired(false);
    criteria.setBearingRequired(false);
    criteria.setCostAllowed(true);
    criteria.setPowerRequirement(Criteria.POWER_LOW);
    String provider = locationManager.getBestProvider(criteria, true);      

    Location location = locationManager.getLastKnownLocation(provider);
    updateWithNewLocation(location);

    //updates location every 5second+5meters
    locationManager.requestLocationUpdates(provider, 5000, 5,
            locationListener);
  }

private final LocationListener locationListener = new LocationListener() {
    public void onLocationChanged(Location location) {
      updateWithNewLocation(location);
    }

    public void onProviderDisabled(String provider){
      updateWithNewLocation(null);
    }

    public void onProviderEnabled(String provider){ }
    public void onStatusChanged(String provider, int status, 
                                Bundle extras){ }
  };

  private void updateWithNewLocation(Location location) {
    String latLongString;
    TextView myLocationText; 
    myLocationText = (TextView)findViewById(R.id.myLocationText);
    if (location != null) {
      double lat = location.getLatitude();
      double lng = location.getLongitude();
      latLongString = "Lat:" + lat + "\nLong:" + lng;
    } else {
      latLongString = "No location found"; 
    }
    myLocationText.setText("Your Current Location is:\n" + 
                           latLongString);
  }   
}

Answer 1

您需要确保 GPS 确实已启用。 此答案适用于 Android 1.6，请参阅如何检查 GPS 接收器的当前状态？ 对于更高版本。

Answer 2

String provider = locationManager.getBestProvider(criteria, true);  

当没有找到合适的提供者时，getBestProvider 将返回 null。你还没有处理过这个案子。