Question

我正在尝试从JSON文件中读取信息，我将在我的Android应用程序中使用它（我使用的是android studio）。好像代码能够读取并保存整个文件，但是无法找到我想要的信息？这是我试图阅读的JSON文件：http://www.ime.ntnu.no/api/course/tma4100。谁能告诉我我做错了什么？谢谢。

public class JSONTask extends AsyncTask<String,String,String> {

private Fag nyttFag;

@Override
protected String doInBackground(String... params) {

    HttpURLConnection urlConnection = null;
    BufferedReader reader = null;


    try {
        URL url = new URL(params[0]);
        urlConnection = (HttpURLConnection) url.openConnection();
        urlConnection.connect();

        //read from API

        InputStream stream = urlConnection.getInputStream();
        reader = new BufferedReader(new InputStreamReader(stream));


        StringBuffer buffer = new StringBuffer();

        String line = "";
        while ((line = reader.readLine()) != null) {
            buffer.append(line);
        }

        String finalJson = buffer.toString();

        //Get objekt course from the whole API
        JSONObject parentObject = new JSONObject(finalJson);
        JSONObject course = parentObject.getJSONObject("course");

        StringBuffer finalBufferedData = new StringBuffer();
        //JSONObject finalObject = parentObject2.getJSONObject(0);
        String coursename = course.getString("name");
        String code = course.getString("code");
        System.out.println(coursename);
        finalBufferedData.append(code + "-" +  coursename + "\n");
        nyttFag = new Fag(code,coursename);

        return finalBufferedData.toString();

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException ex) {
        ex.printStackTrace();
    } catch (JSONException e) {
        e.printStackTrace();
    } finally {
        if (urlConnection != null) {
            urlConnection.disconnect();
        }
        try {
            if (reader != null) {
                reader.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return null;
}

@Override
protected void onPostExecute(String result) {
    super.onPostExecute(result);
    MainActivityProfessor.fagData.setText(result);
    if (!navnPåFag.contains(nyttFag.name)) {
        navnPåFag.add(nyttFag.name);
    }
}

}

Answer 1

你需要证明JSON正在被正确下载，我建议在线上进行一些调整：

JSONObject parentObject = new JSONObject(finalJson);

验证是否正确解析了 finalJson ，然后验证 course 变量是否真正成为JSONObject。

使用ASYNC Task读取JSON文件

1 个答案: