[英]Why the function getLastKnownLocation return Null on Android SDK?
[英]android getLastKnownLocation() return always return null
我正在创建一个只在用户点击按钮时检查位置的应用。
这是我的代码,当我调用getLastKnownLocation时它返回null,即使在我调用requestLocationUpdates之后:
public void main(String[] args, int iteration, Context context){
Criteria criteria = new Criteria();
LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
LocationListener loc_listener = new LocationListener() {
public void onLocationChanged(Location l) {
}
public void onProviderEnabled(String p) {}
public void onProviderDisabled(String p) {}
public void onStatusChanged(String p, int status, Bundle extras) {}
};
String bestProvider = locationManager.getBestProvider(criteria, false);
locationManager.requestLocationUpdates(bestProvider, 0, 0, loc_listener);
Location location = locationManager.getLastKnownLocation(bestProvider);
location = locationManager.getLastKnownLocation(bestProvider);
double lat;
double lon;
try {
lat = location.getLatitude();
lon = location.getLongitude();
} catch (NullPointerException e) {
lat = -1.0;
lon = -1.0;
}
Log.i("results:", String.valueOf(lat) + " " + String.valueOf(lon) + " 10NN");}}
设备上的位置服务已启用。 非常感谢!
getLastKnownLocation将返回null,直到触发回调onLocationChanged()为止。 即使天空清晰可见,GPS也可能需要几分钟。 如果你在室内,它可能永远不会运行。 你必须等待它运行。
试试这个
mGoogleMap.setOnMyLocationButtonClickListener(new OnMyLocationButtonClickListener() {
@Override
public boolean onMyLocationButtonClick()
{
Location myLocation = mGoogleMap.getMyLocation();
onLocationChanged(myLocation);
return false;
}
});
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