Android Geocoder getFromLocationName总是返回null [英] Android Geocoder getFromLocationName always returns null

问题描述

我一直在尝试对字符串进行地理编码以获取其坐标，但是我的程序总是崩溃，因为当我尝试使用 getFromLocationName（）它返回空。我一直在努力解决这个问题，但没有任何工作。这是我的代码

I have been trying to geocode a string to get its coordinates but my program always crashes because when ever I try to use getFromLocationName() it returns null. I have been trying to fix this for hours but nothing is working. Here is my code

public class MainActivity extends Activity {

    private GoogleMap mMap;

    List<Address> addresses;
    MarkerOptions miami;
    String myLocation = "Miami,Florida";

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (mMap == null) {
            mMap = ((MapFragment) getFragmentManager().findFragmentById(
                    R.id.map)).getMap();
        }

        if (mMap != null) {

            Geocoder geocoder = new Geocoder(this);


            double latitude = 0;
            double longitude = 0;

            while(addresses==null){
            try {
                addresses = geocoder.getFromLocationName(myLocation, 1);

            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            }
            Address address = addresses.get(0);
            if (addresses.size() > 0) {
                latitude = address.getLatitude();
                longitude = address.getLongitude();
            }
            LatLng City = new LatLng(latitude, longitude);

            miami = new MarkerOptions().position(City).title("Miami");

            mMap.addMarker(miami);

            mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(City, 15));

        }
}

推荐答案

Geocoder并不总是返回值。您可以尝试在for循环中发送请求3次。我应该能够返回至少一次。如果不是，他们可能是一个连接问题，或者可能是其他问题，如服务器不回复您的请求。尝试看看这些线程：

Geocoder doesn't always return a value. You can try to send a request 3 times in a for loop. I should be able to return atleast once. If not then, their might be a connection issue or can be other issues like server dis not reply to your request. Try and see these threads:

Geocoder并不总是返回值，而 geocoder.getFromLocationName只返回null

更新：

我有一段时间的循环，但我用来最多尝试10次。有时候，即使连接互联网，它也没有返回任何东西。然后，我每次都使用这个更可靠的方法： / p>

I had a while loop as well but I used to try it maximum for 10 times. Sometimes, it never returned anything even if it was connected t internet. Then, I used this much more reliable way to get the address everytime:

public JSONObject getLocationInfo() {

        HttpGet httpGet = new HttpGet("http://maps.google.com/maps/api/geocode/json?latlng="+lat+","+lng+"&sensor=true");
        HttpClient client = new DefaultHttpClient();
        HttpResponse response;
        StringBuilder stringBuilder = new StringBuilder();

        try {
            response = client.execute(httpGet);
            HttpEntity entity = response.getEntity();
            InputStream stream = entity.getContent();
            int b;
            while ((b = stream.read()) != -1) {
                stringBuilder.append((char) b);
            }
        } catch (ClientProtocolException e) {
            } catch (IOException e) {
        }

        JSONObject jsonObject = new JSONObject();
        try {
            jsonObject = new JSONObject(stringBuilder.toString());
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return jsonObject;
    }

我打电话给如下：

JSONObject ret = getLocationInfo(); 
JSONObject location;
String location_string;
try {
    location = ret.getJSONArray("results").getJSONObject(0);
    location_string = location.getString("formatted_address");
    Log.d("test", "formattted address:" + location_string);
} catch (JSONException e1) {
    e1.printStackTrace();

}

希望这有帮助。我也厌倦依靠geocoder。这对我有用
如果用URL和经度坐标替换URL，并在Web浏览器中查看返回的JSON对象。你会看到刚刚发生的事情。

Hope this helps. I was also tired of relying on geocoder. This worked for me. If you replace the URL with the lat and longitude coordinates and see the returned JSON object in a web browser. You'll see what just happened.

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