无法获取 JSON 格式的数据

Posted 2023-04-19

【中文标题】无法获取 JSON 格式的数据

【英文标题】：Can't get data in JSON format

【发布时间】：2020-11-25 12:12:10

【问题描述】：

我想为我的应用程序获取 JSON 格式的数据，我尝试了不同的方法来解决这个问题，但是我在这个错误中找不到答案。我希望你们能帮助我，如果您需要更多详细信息，请告诉我。

这是我得到的错误：

E/MainActivity: Problem parsing the earthquake JSON results
    org.json.JSONException: End of input at character 0 of 
        at org.json.JSONTokener.syntaxError(JSONTokener.java:460)
        at org.json.JSONTokener.nextValue(JSONTokener.java:101)
        at org.json.JSONObject.<init>(JSONObject.java:164)
        at org.json.JSONObject.<init>(JSONObject.java:181)
        at com.example.android.soonami.MainActivity$TsunamiAsyncTask.extractFeatureFromJson(MainActivity.java:207)
        at com.example.android.soonami.MainActivity$TsunamiAsyncTask.doInBackground(MainActivity.java:121)
        at com.example.android.soonami.MainActivity$TsunamiAsyncTask.doInBackground(MainActivity.java:104)
        at android.os.AsyncTask$3.call(AsyncTask.java:378)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:289)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:919)

提取json格式数据的方法：

private Event extractFeatureFromJson(String earthquakeJSON) 
            try 
                JSONObject baseJsonResponse = new JSONObject(earthquakeJSON);
                JSONArray featureArray = baseJsonResponse.getJSONArray("features");

                // If there are results in the features array
                if (featureArray.length() > 0) 
                    // Extract out the first feature (which is an earthquake)
                    JSONObject firstFeature = featureArray.getJSONObject(0);
                    JSONObject properties = firstFeature.getJSONObject("properties");

                    // Extract out the title, time, and tsunami values
                    String title = properties.getString("title");
                    long time = properties.getLong("time");
                    int tsunamiAlert = properties.getInt("tsunami");

                    // Create a new @link Event object
                    return new Event(title, time, tsunamiAlert);
                
             catch (JSONException e) 
                Log.e(LOG_TAG, "Problem parsing the earthquake JSON results", e);
            
            return null;
        

将数据放入Event对象的方法：

@Override
        protected Event doInBackground(URL... urls) 
            // Create URL object
            URL url = createUrl(USGS_REQUEST_URL);

            // Perform HTTP request to the URL and receive a JSON response back
            String jsonResponse = "";
            try 
                jsonResponse = makeHttpRequest(url);
             catch (IOException e) 
                // TODO Handle the IOException
                e.printStackTrace();
            

            // Extract relevant fields from the JSON response and create an @link Event object
            Event earthquake = extractFeatureFromJson(jsonResponse);

            // Return the @link Event object as the result fo the @link TsunamiAsyncTask
            return earthquake;
        

【参考方案1】：

我猜你收到了来自jsonResponse = makeHttpRequest(url) 的空字符串。 你检查过吗？