如何在android中使用json數組限制問題的長度？

Question

嘿家伙我正在開發一個測驗，在我有50個問題存儲，然后我想要10個問題只顯示..問題是隨機顯示..但我的問題是它應該是10個問題，以顯示在測驗。請幫助我...幫助真的很感激..

public class Question1 extends Activity {



Intent menu = null;
BufferedReader bReader = null;
static JSONArray quesList = null;
static int index = 50;



/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.question10);

    Thread thread = new Thread() {
        public void run() {
            try {
                Thread.sleep(1 * 1000);
                finish();
                loadQuestions();
                Intent intent = new Intent(Question1.this,
                        Question2.class);
                Question1.this.startActivity(intent);
            } catch (Exception e) {
            }
        }
    };
    thread.start();

}

private void loadQuestions() throws Exception {
    try {



        InputStream questions = this.getBaseContext().getResources()
                .openRawResource(R.raw.questions);
        bReader = new BufferedReader(new InputStreamReader(questions));
        StringBuilder quesString = new StringBuilder();
        String aJsonLine = null;
        while ((aJsonLine = bReader.readLine()) != null) {
            quesString.append(aJsonLine);
        }

        Log.d(this.getClass().toString(), quesString.toString());
        JSONObject quesObj = new JSONObject(quesString.toString());
        quesList = quesObj.getJSONArray("Questions");
        Log.d(this.getClass().getName(),
                "Num Questions " + quesList.length());


    } catch (Exception e) {

    } finally {
        try {
            bReader.close();
        } catch (Exception e) {
            Log.e("", e.getMessage().toString(), e.getCause());
        }

    }

}

public static JSONArray getQuesList()throws JSONException{

      Random rnd = new Random();

        for (int i = quesList.length() - 1; i >= 0; i--)
        {
          int j = rnd.nextInt(i + 1);
          // Simple swap
          Object object = quesList.get(j);
          quesList.put(j, quesList.get(i));
          quesList.put(i, object);
        }
        return quesList;


}

Answer 1

由於您希望在每個測驗中都有動態10個問題，您可以使用Collections.shuffle(YourList) ArrayList進行混洗，並從該混洗列表中取10個問題。

但是，當您擁有JSONArray時，您必須迭代它並准備ArrayList，這樣您就可以使用shuffle() 。

更新：

請參閱ogzd的答案，還有你將有問題的一種方式List<JsonObject>現在你只需要調用洗牌方法，我所提到的：

Collections.shuffle(questions);

現在，它將隨機播放問題列表，因此您必須復制或從中獲取前10個項目。

Answer 2

嘗試：

 List<JsonObject> questions = new ArrayList<JsonObject>();
 int n = Math.min(10, quesList.length());
 for(int i = 0; i < n; i++) {
     JsonObject question = quesList.getJsonObject(i);
     questions.add(question);
 }