android - android中的Json token 错误

Question

我试图在没有网络连接时运行我的项目。如果网络可用，则不会出现问题。

我遇到了这个错误，

01-24 17:41:19.725: E/AndroidRuntime(1077): FATAL EXCEPTION: AsyncTask #3
01-24 17:41:19.725: E/AndroidRuntime(1077): java.lang.RuntimeException: An error occured while executing doInBackground()
01-24 17:41:19.725: E/AndroidRuntime(1077):     at  android.os.AsyncTask$3.done(AsyncTask.java:299)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at java.util.concurrent.FutureTask.run(FutureTask.java:239)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at java.lang.Thread.run(Thread.java:856)
01-24 17:41:19.725: E/AndroidRuntime(1077): Caused by: java.lang.NullPointerException
01-24 17:41:19.725: E/AndroidRuntime(1077):     at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at org.json.JSONTokener.nextValue(JSONTokener.java:94)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at org.json.JSONObject.<init>(JSONObject.java:154)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at org.json.JSONObject.<init>(JSONObject.java:171)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at com.example.sms.JsonParser.makeHttpRequest(JsonParser.java:136)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at co m.example.sms.LoginActivity$AttemptLogin.doInBackground(LoginActivity.java:298)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at com.example.sms.LoginActivity$AttemptLogin.doInBackground(LoginActivity.java:1)
01-24 17:41:19.725: E/AndroidRuntime(1077):     at 

这是我的 JsonParser 类，

  public JSONObject makeHttpRequest(String url, String method,
        List<NameValuePair> params) {


    try {

        json=null;
        jsonObject= null;
        if(method.equalsIgnoreCase("POST")){


            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            httpPost.setEntity(new UrlEncodedFormEntity(params));

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();

            System.out.println(is);

            System.out.println("getting the content");

        }else if(method.equalsIgnoreCase("GET")){

            DefaultHttpClient httpClient = new DefaultHttpClient();
            String paramString = URLEncodedUtils.format(params, "utf-8");
            url += "?" + paramString;
            HttpGet httpGet = new HttpGet(url);

            HttpResponse httpResponse = httpClient.execute(httpGet);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();

        }           

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }


    System.out.println("getting  all the values ");

    try {    
        json = null;
        jsonObject =null;
        BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);


       StringBuilder sb = new StringBuilder();
        String line = null;

        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }

        is.close();

        json = sb.toString();    


    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }


    try {

        Log.i("tagconvertstr1", "["+json+"]");
        //if(TextUtils.isEmpty(json))
        if(json!=null||json!="null")
        {
            jss= "not empty";
            System.out.println("json is not equal to null");
           jsonObject = new JSONObject(json);
          System.out.println("json object parse finished");

        Log.i("tagconvertstr2","["+json+"]");

        }

        else
        {
            System.out.println(" it is null value ");
            jss= "empty";
            System.out.println("jss value is" +jss);

        }


    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }


    System.out.println("jsson object is" + json);

    return jsonObject;

}

我不知道为什么即使我检查了 null 也会出现此错误!任何人都可以帮助我吗？

Answer 1

正如您所说，网络断开时会发生此错误。这意味着您收到 NULL 值并将 NULL 值传递给 json。如果将 null 分配给构造函数，则 JSONObject 无法捕获错误。因此，要解决此问题，请替换以下代码

jsonObject=new JSONObject(json) ;

到

jsonObject=new JSONObject(json == null ? "" : json) ;