Question

问候！我删除了硬编码的json数据并移动到从url请求数据。我有异常错误。代码与最终官方git几乎相同，但我收到了错误。

我从json中提取数据的代码是： private static final String USGS_REQUEST_URL = “http://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&orderby=time&minmag=5&limit=10”;

//
  public static List<Earthquake> extractFeaturesfromJson(String earthquakeJSON) {
        /*if the json is null then return earlu*/
        if (TextUtils.isEmpty(earthquakeJSON)) {
            return null;
        }

        // Create an empty ArrayList that we can start adding earthquakes to
        List<Earthquake> earthquakes = new ArrayList<>();

        // Try to parse the JsonResponseString. If there's a problem with the way the JSON
        // is formatted, a JSONException exception object will be thrown.
        // Catch the exception so the app doesn't crash, and print the error message to the logs.
        try {
            // create an object form jsonString
            JSONObject root = new JSONObject(earthquakeJSON);
            JSONArray features = root.getJSONArray("features");

            for (int i = 0; i < features.length(); i++) {
                // Get a single earthquake at position i within the list of earthquakes
                JSONObject currentEarthquake = features.getJSONObject(i);
                // For a given earthquake, extract the JSONObject associated with the
                // key called "properties", which represents a list of all properties
                // for that earthquake.
                JSONObject properties = currentEarthquake.getJSONObject("properties");

                double mag = properties.getDouble("mag");
                String location = properties.getString("place");
                long time = properties.getLong("time");

                //extract the value of key url
                String url = properties.getString("url");
                //create new object with magnitude, location ane time and url from json response
                Earthquake earthquake = new Earthquake(mag, location, time, url);
                earthquakes.add(earthquake);


            }


        } catch (JSONException e) {
            // If an error is thrown when executing any of the above statements in the "try" block,
            // catch the exception here, so the app doesn't crash. Print a log message
            // with the message from the exception.
            Log.e("QueryUtils", "Problem parsing the earthquake JSON results", e);
        }

        // Return the list of earthquakes
        return earthquakes;
    }

logcat显示：

09-26 14:49:23.628 2551-2584/com.example.android.quakereport E/com.example.android.quakereport.QueryUtils: Problem retrieving the earthquake JSON results.

Answer 1

您网址中的json数据格式不正确。将您从网址收到的内容与硬编码数据进行比较。

Answer 2

此方法在后台工作完成后在主UI线程上运行完成。此方法接收来自doInBackground()方法的返回值作为输入。

首先我们清除适配器，以摆脱以前的地震数据查询USGS。

然后我们使用新的地震列表更新适配器，这将触发ListView重新填充其列表项。 但是在将数据填充到适配器时犯了错误。

        @Override
        protected void onPostExecute(List<Earthquake> data) {
            //clear the adapter of previdous earthquake data
            mAdapter.clear();
            if (data != null && data.isEmpty()) { //====?????shourld be !data.isEmpty())
                mAdapter.addAll(data);
            }
        }

真正的问题是onPostExecute方法在后台方法执行后填充mainthread中的数据。

Answer 3

如果你正在使用Udacity android课程并遇到quakereport / DidUfeelIt应用程序的此错误，那么更改URL并尝试使用其他URL来解决您的问题。例如： - 课程期间提供的URL是＆＃34; http://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&starttime=2012-01-01&endtime=2012-12-01&minmagnitude=6＆＃34;

然后我得到了同样的错误，即＃34;解析JSON＆＃34; 所以我尝试了不同的URL： https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/4.5_day.geojson

它有效.. !! 在课程期间，始终尝试从USGS网站获取最新的URL。

Answer 4

将您的请求网址更改为USGS_REQUEST_URL =“https://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&orderby=time&minmag=6&limit=10”

区别在于使用https而不是http。

根据USGS网站的API文档，该网站现在使用安全超文本传输协议（https） https://earthquake.usgs.gov/fdsnws/event/1/

Answer 5

使用在线Json验证器。 http://jsonlint.com/ 他们将验证json是否有问题。

解析json结果时出错？

5 个答案: