为什么For循环重复值

Question

我试图从服务器获取一些值，一切正常但是由于某种原因我收到重复的值，服务器包含3个键和值但是在我的代码中它显示了6个键和值，请建议可能导致这种情况的原因。

FirstActivity.java

public void getGifts() {
    Communicator.getInstance().on("initializeRoom", new Emitter.Listener() {

        @Override
        public void call(Object... args) {
            JSONDictionary response = (JSONDictionary) args[0];
            String str = response.get("data").toString();
            try {
                JSONObject dataJSo = new JSONObject(str);
                JSONArray giftsData = dataJSo.getJSONArray("gifts");
                for (int i = 0; i < giftsData.length(); i++) {
                    JSONObject gifts = (JSONObject) giftsData.get(i);
                    giftsId = (Integer) gifts.get("id");
                    giftsPrice = (Integer) gifts.get("price");
                    giftsMinLevel = (String) gifts.get("minLevel");
                    giftsUrl = (String) gifts.get("urlFile");
                    giftsArray.add(new GiftsModel(giftsId, giftsPrice, 
                                    giftsUrl, giftsMinLevel));

                }

                Singleton.instance().cache = giftsArray;

            } catch (JSONException e) {
                e.printStackTrace();
            }
        }

    });

}

SecondActivity.java

public class SecondActivity{

      ArrayList<GiftsModel> giftsArray = Singleton.instance().cache;

      //And some code

}

Singleton.java

public class Singleton {
private Singleton() {}

static Singleton obj= null;
public static Singleton instance() {
    if (obj == null) {
        obj = new Singleton();
    }
    return obj;
}

public ArrayList<GiftsModel> cache;
}