尝试将我的地图居中放在用户位置（表示位置为空） [英] Trying to center my map on user location (Says location is null)

问题描述

一直试图在用户位置上居中放置一张地图，但它一直说latLng变量为空。我读过那种情况，因为我使用getLastKnownLocation，但我无法找到任何其他方式来做到这一点（我是编程新手）。我正在使用Jellybean上的google api。这是我正在使用的代码。

  if（ContextCompat.checkSelfPermission（this，Manifest.permission.ACCESS_FINE_LOCATION）
 == PackageManager.PERMISSION_GRANTED）{
 mMap.setMyLocationEnabled（true）; 
 
 LocationManager locationManager =（LocationManager）getSystemService（Context.LOCATION_SERVICE）; 
标准标准=新标准（）; 
 String provider = locationManager.getBestProvider（criteria，true）; 
位置myLocation = locationManager.getLastKnownLocation（provider）; 
 
 //纬度y纵向
双纬度= myLocation.getLatitude（）; 
 double longitude = myLocation.getLongitude（）; 
 LatLng latLng =新LatLng（经度，纬度）; 
 // Mover el mapa a la posicion actual del usuario 
 mMap.moveCamera（CameraUpdateFactory.newLatLng（latLng））; 
 //放大
 mMap.animateCamera（CameraUpdateFactory.zoomTo（12））; 
 mMap.addMarker（new MarkerOptions（）。position（new LatLng（latitude，longitude））。title（You are here！）。snippet（考虑自己定位））; 
 
 
 
 
 
 
}其他{
 //显示原理和请求权限。 
 
  

解决方案

检查AndroidManifest。 xml

 < user-permission android：name =android.permission.ACCESS_FINE_LOCATION /> 
< user-permission android：name =android.permission.ACCESS_COARSE_LOCATION /> 
< user-permission android：name =android.permission.INTERNET /> 
  

主要我们可以通过GPS提供商和网络提供商获取位置信息。
如果我们通过GPS提供商获得空位置，则将提供商更改为NETWORK。

$ b

  LocationManager locationManager =（LocationManager）getSystemService （Context.LOCATION_SERVICE）; 
字符串provideGps = locationManager.GPS_PROVIDER; 
字符串provideNetwork = locationManager.NETWORK_PROVIDER; 
 
位置位置= locationManager.getLastKnownLocation（providerGps）; 
 
如果（location == null）{
 location = locationManager.getLastKnownLocation（providerNetwork）; 
 location.getLatitude（）; 
 location.getLongitude（）; 
} else {
 location.getLatitude（）; 
 location.getLongitude（）; 
} 
  

ive been trying to center a map on the users location, but it keeps saying the latLng variable is null. I have read that that happens because i am using the getLastKnownLocation, but I cant find any other way to do it (I am new to programing). I am working with the google api on Jellybean. Here is the code that i am using.

if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            mMap.setMyLocationEnabled(true);

 LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
      Criteria criteria = new Criteria();
        String provider = locationManager.getBestProvider(criteria,true);
        Location myLocation = locationManager.getLastKnownLocation(provider);

        //Latitude y longitud
        double latitude = myLocation.getLatitude();
        double longitude = myLocation.getLongitude();
        LatLng latLng = new LatLng(latitude,longitude);
        //Mover el mapa a la posicion actual del usuario
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
        //Zoom
        mMap.animateCamera(CameraUpdateFactory.zoomTo(12));
        mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("You are here!").snippet("Consider yourself located"));






      } else {
            // Show rationale and request permission.
        }

解决方案

Check permission in "AndroidManifest.xml

<user-permission android:name="android.permission.ACCESS_FINE_LOCATION />
<user-permission android:name="android.permission.ACCESS_COARSE_LOCATION />
<user-permission android:name="android.permission.INTERNET />

Mainly We can get location via GPS Provider and NETWORK provider. If we get null location Via GPS provider, then change Provider to NETWORK.

LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
String provideGps = locationManager.GPS_PROVIDER;
String provideNetwork = locationManager.NETWORK_PROVIDER;

Location location = locationManager.getLastKnownLocation(providerGps);

If (location == null) {
    location = locationManager.getLastKnownLocation(providerNetwork);
    location.getLatitude();
    location.getLongitude();
} else {
    location.getLatitude();
    location.getLongitude();
}

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