使用ASYNC讀取JSON文件任務

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我想從JSONfile中讀取信息，我將在我的Android應用程序（我正在使用android studio）中使用它。看起來代碼能夠讀取並保存整個文件，但無法挑選出我想要的信息？這是我試圖讀取的JSON文件：http://www.ime.ntnu.no/api/course/tma4100。誰能告訴我我做錯了什麼？ Thankyou。使用ASYNC讀取JSON文件任務

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); 
    } 
}

}

來源

2017-02-23 Nina

你需要證明該JSON被正確下載，我建議就行了一些debbuging：

JSONObject parentObject = new JSONObject(finalJson);

驗證是否finalJson是正確的解析後，如果當然變量真的成爲一個JSONObject。

來源

2017-02-23 14:06:48 Balbinator

使用ASYNC讀取JSON文件任務

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