java - Json类型不匹配: Cannot convert to string

Question

我正在开发一个程序，该程序将发布到服务器并检索 json 对象，然后将其转换为字符串数组。

当我在浏览器上测试结果时，我得到以下结果:

{"Bookname":["Alive-O","All Write Now ","Bun Go Barr 1","Planet Maths","Small World"],"SubjectName":["Religion","English","Irish","Maths","Science"]}

这是我发布和转换字符串的类:

try {
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost("http://cosy.azurewebsites.net/bookrequest.php");

    User user = userLocalStore.getLoggedInUser();

    String username = user.username;

    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
    nameValuePairs.add(new BasicNameValuePair( "Username", username ));
    httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

    HttpResponse response = httpclient.execute(httppost);
    HttpEntity entity = response.getEntity();


    String result = EntityUtils.toString(entity);
    JSONObject jsonObject = new JSONObject(result);

    JSONArray jsonArray = jsonObject.getJSONArray("Bookname");
    BookName = new String[jsonArray.length()];
    for (int i = 0; i < jsonArray.length(); i++) {
        BookName[i] = jsonArray.getString(i);
    }

    // for getting subjectnames
    Log.v("we're getting a subject", "2");

    jsonArray = jsonObject.getJSONArray("SubjectName");
    BookSubject = new String[jsonArray.length()];
    for (int i = 0; i < jsonArray.length(); i++) {
        BookSubject[i] = jsonArray.getString(i);
    }

} 

这是我的日志猫告诉我的:

02-21 18:15:35.538    1436-3694/net.azurewebsites.cosy W/System.err﹕ org.json.JSONException: Value [] of type org.json.JSONArray cannot be converted to JSONObject
02-21 18:15:35.538    1436-3694/net.azurewebsites.cosy W/System.err﹕ at org.json.JSON.typeMismatch(JSON.java:111)
02-21 18:15:35.538    1436-3694/net.azurewebsites.cosy W/System.err﹕ at org.json.JSONObject.<init>(JSONObject.java:159)
02-21 18:15:35.538    1436-3694/net.azurewebsites.cosy W/System.err﹕ at org.json.JSONObject.<init>(JSONObject.java:172)
02-21 18:15:35.538    1436-3694/net.azurewebsites.cosy W/System.err﹕ at net.azurewebsites.cosy.Books$getBooks.doInBackground(Books.java:148)
02-21 18:15:35.538    1436-3694/net.azurewebsites.cosy W/System.err﹕ at net.azurewebsites.cosy.Books$getBooks.doInBackground(Books.java:106)
02-21 18:15:35.538    1436-3694/net.azurewebsites.cosy W/System.err﹕ at android.os.AsyncTask$2.call(AsyncTask.java:288)
02-21 18:15:35.538    1436-3694/net.azurewebsites.cosy W/System.err﹕ at java.util.concurrent.FutureTask.run(FutureTask.java:237)
02-21 18:15:35.542    1436-3694/net.azurewebsites.cosy W/System.err﹕ at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
02-21 18:15:35.542    1436-3694/net.azurewebsites.cosy W/System.err﹕ at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
02-21 18:15:35.542    1436-3694/net.azurewebsites.cosy W/System.err﹕ at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
02-21 18:15:35.542    1436-3694/net.azurewebsites.cosy W/System.err﹕ at java.lang.Thread.run(Thread.java:841)

我试图将其用作类中的数组。

Answer 1

该错误表明您正在尝试将 JSONArray 转换为 JSONObject，这意味着此指令:

JSONObject jsonObject = new JSONObject(result);

有问题。您获得的 JSON 很有可能被括号包围(因为您是在浏览器中测试的，而不是在移动设备上测试的)。尝试改变:

JSONObject jsonObject = new JSONObject(result);

至

JSONArray obj = new JSONArray(result);
JSONObject jsonObject = obj.getJSONObject(0);