凌空对象请求返回0 [英] Volley Object request Returning 0

问题描述

我有一个包含6行的远程数据库.
这是我的代码，我将其放入列表中，以便获取尺寸，
但是它总是返回0.

I Have a Remote Database that contains 6 rows.
Here's my code, I put it in List so that i can get the size,
But it's always returning 0.

public List<Comments> getComments() {
        final List<Comments> commentsData = new ArrayList<>();
        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST,
                showUrl, new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                try {
                    JSONArray jsonArray = response.getJSONArray("poi");
                    for (int i = 0; i < jsonArray.length(); i++) {
                        JSONObject jsonObject = jsonArray.getJSONObject(i);
                        Comments current = new Comments();
                        current.image = "drawable://" + R.drawable.juandirection_placeholder;
                        current.title = jsonObject.getString("title");
                        current.comment = jsonObject.getString("comment");
                        current.date = jsonObject.getString("date");
                        current.rating = Integer.parseInt(jsonObject.getString("rating"));
                        commentsData.add(current);
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });

        VolleyHelper.getInstance(getApplicationContext()).addToRequestQueue(jsonObjectRequest);
        return commentsData;
    }

我需要一些尺寸供使用.
为什么总是返回零?
我什至尝试在for循环中添加一个counter ++.
但是当我得到计数​​器的值时，它仍然为零.

I need the size for some use.
Why is it always returning zero?
I even tried adding a counter++ inside for loop.
But when i get the value of the counter its still zero.

推荐答案

JsonObjectRequest在后台线程上运行.这就是为什么列表大小为0的原因.必须使用public void onResponse(JSONObject response) {}函数.

JsonObjectRequest run on a background thread. That's why you getting the list size 0. you must work into the public void onResponse(JSONObject response) {} function .

示例.

@Override
        public void onResponse(JSONObject response) {
            try {
                JSONArray jsonArray = response.getJSONArray("poi");
                for (int i = 0; i < jsonArray.length(); i++) {
                    JSONObject jsonObject = jsonArray.getJSONObject(i);
                    Comments current = new Comments();
                    current.image = "drawable://" + R.drawable.juandirection_placeholder;
                    current.title = jsonObject.getString("title");
                    current.comment = jsonObject.getString("comment");
                    current.date = jsonObject.getString("date");
                    current.rating = Integer.parseInt(jsonObject.getString("rating"));
                    commentsData.add(current);
                }

                // **you may call function and pass the list value to update your ui component. you will get the real size of list here.**

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

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