求两个地观测点之间驱动距离时的例外情况

Question

我想找出两个纬度和经度之间的行车距离。这是我的密码

private String GetDistance(LatLng origin, LatLng dest) {

        // Origin of route
        String str_origin = "origin=" + origin.latitude + ","
                + origin.longitude;
        // Destination of route
        String str_dest = "destination=" + dest.latitude + "," + dest.longitude;
        // Sensor enabled
        String sensor = "sensor=false";
        // Building the parameters to the web service
        String parameters = str_origin + "&" + str_dest + "&" + sensor;
        // Output format
        String output = "json";
        // Building the url to the web service
        String urlString = "https://maps.googleapis.com/maps/api/directions/"
                + output + "?" + parameters;

        // get the JSON And parse it to get the directions data.
        HttpURLConnection urlConnection = null;
        URL url = null;
        try {
            url = new URL(urlString.toString());
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.setDoOutput(true);
            urlConnection.setDoInput(true);
            urlConnection.connect();

            InputStream inStream = urlConnection.getInputStream();
            BufferedReader bReader = new BufferedReader(new InputStreamReader(
                    inStream));

            String temp,response = "";
            while ((temp = bReader.readLine()) != null) {
                // Parse data
                response += temp;
            }
            // Close the reader, stream & connection
            bReader.close();
            inStream.close();
            urlConnection.disconnect();

            // Sort out JSONresponse
        //  JSONObject object = (JSONObject) new JSONTokener(response)
        //          .nextValue();
            JSONObject object = new JSONObject(response);
            JSONArray array = object.getJSONArray("routes");
            // Log.d("JSON","array: "+array.toString());

            // Routes is a combination of objects and arrays
            JSONObject routes = array.getJSONObject(0);
            // Log.d("JSON","routes: "+routes.toString());

            String summary = routes.getString("summary");
             Log.d("JSON","summary: "+summary);

            JSONArray legs = routes.getJSONArray("legs");
            // Log.d("JSON","legs: "+legs.toString());

            JSONObject steps = legs.getJSONObject(0);
            // Log.d("JSON","steps: "+steps.toString());

            JSONObject distance = steps.getJSONObject("distance");
            // Log.d("JSON","distance: "+distance.toString());

            sDistance = distance.getString("text");
            iDistance = distance.getInt("value");  

        } catch (Exception e) {
            // TODO: handle exception
            return e.toString();
        }

        return sDistance;
    }

我得到了一个例外

org.json.JSONException:Index 0 out of range [0..0)

这是我的stacktrace

Ljava.lang.StackTraceElement;@41019be8

请帮我解决问题是什么。

Answer 1

首先，不要硬编码从数组中获得的任何位置（如0）。Bcs，数组可能为空。

你的案子就是这样。您的array或legsJSONArray中的一个是空的，但您正在尝试获取它们的第0个位置。因此，它正在抛出索引超出范围的异常。

要从数组中获取值，更好地使用for循环。一个示例代码段是：

Log.v("array-length--", ""+array.length());

for(int i=0; i < array.length();i++)
{
    // Routes is a combination of objects and arrays
    JSONObject routes = array.getJSONObject(i);
    // Log.d("JSON","routes: "+routes.toString());

    String summary = routes.getString("summary");
    Log.d("JSON","summary: "+summary);

    JSONArray legs = routes.getJSONArray("legs");
    // Log.d("JSON","legs: "+legs.toString());

    Log.v("legs-length--", ""+legs.length());

    for(int j=0; j < legs.length(); j++)
    {
        JSONObject steps = legs.getJSONObject(j);
        // Log.d("JSON","steps: "+steps.toString());

        JSONObject distance = steps.getJSONObject("distance");
        // Log.d("JSON","distance: "+distance.toString());

        sDistance = distance.getString("text");
        iDistance = distance.getInt("value"); 
    }

}