Question

当我使用Retrofit调用lon，lat来自服务器时，数据就在这里;

Double lon，lat;

NetworkEngine.getInstance().getResDetail(id, new Callback<Restaurant>() {
            @Override
            public void success(Restaurant restaurant, Response response) {

                    lon = restaurant.getLon(); // Double
                    lat = restaurant.getLat(); // Double
                    Log.i("lon_", String.valueOf(restaurant.getLon())); //    lon_: -128.861048
                    Log.i("lat_", String.valueOf(restaurant.getLat())); //    lat_: 51.09783    
            }

但@onMapReady lon，lat为null。为什么呢？

@Override
public void onMapReady(GoogleMap googleMap) {

    Log.i("lonn_", String.valueOf(lon)); // null
    Log.i("latt_", String.valueOf(lat)); // null
    map = googleMap;
    LatLng location = new LatLng(lat, lon);

}

Answer 1

在您的Retrofit API调用之前调用onMapReady()。

在您的Retrofit API调用的mapFragment.getMapAsync(this);方法中初始化您的success()。

Answer 2

@onMapReady lon，lat为null。为什么呢？

因为lon和lat在这里没有值意味着两者都是null。我想你是在网络通话之前打开地图。你应该这样做 -

NetworkEngine.getInstance().getResDetail(id, new Callback<Restaurant>() {
    @Override
    public void success(Restaurant restaurant, Response response) {

            lon = restaurant.getLon(); // Double
            lat = restaurant.getLat(); // Double
            Log.i("lon_", String.valueOf(restaurant.getLon())); //    lon_: -128.861048
            Log.i("lat_", String.valueOf(restaurant.getLat())); //    lat_: 51.09783    
            openMap();// it's just a method name you can change it with user suitable method name.
    }
}

在 openMap（）方法中执行所有与地图相关的事情。

private void openMap(){
    // do your stuff here..

   // something like to call another method to open map for you or,
  // write all the code here to open a map like this--
  SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
  mapFragment.getMapAsync(this);

}

这只是一个想法，希望它会有所帮助。

lon lat为null @onMapReady

2 个答案: