Android：在排球中更新列表

Question

我想填写互联网上的项目列表。为此，我正在使用凌空抽射。如果我手动将值添加到列表中，它可以工作：

private ArrayList<ImageItem> getData() {

        final ArrayList<ImageItem> imageItems = new ArrayList<>();

        for (int i = 0; i < 6; i++) {
            Bitmap b = null;
            ImageItem imageItem = new ImageItem();
            imageItem.setImageFromDB("http://192.168.192.200/images/q112898055d4-eb4d-41ef-9c00-0069789740c1.jpg");
            imageItems.add(imageItem);
        }
        return imageItems;
    }

但如果我使用凌空，它就不起作用..列表为空。除此之外，我还有一个gridview-adapter的列表。这是我的代码：volley：

private ArrayList<ImageItem> getData() {

        final ArrayList<ImageItem> imageItems = new ArrayList<>();
        final String url = "http://192.168.192.200/getCustomerQuotes.php?9tEqRp93s2t&EsAzJo1EtNM&VuEtfRAPjNU&NTv5hhlsx5Y&uid=112";
        // making fresh volley request and getting json
        JsonObjectRequest jsonReq = new JsonObjectRequest(Request.Method.GET,
                url, null, new Response.Listener<JSONObject>() {

            @Override
            public void onResponse(JSONObject response) {
                Log.e("TAB1ZZ", "url is " + url);
                VolleyLog.d("LIKES", "Response: " + response.toString());
                if (response != null) {

                    try {
                        JSONArray arr = response.getJSONArray("feed");
                        for (int i = 0; i < 5; i++) {
                            JSONObject obj = arr.getJSONObject(i);
                            String imageForDb = StaticVariables.baseUrlForImage + obj.getString("imageName");
                            Log.e("IAMGEFODB", "is " + imageForDb);

                            ImageItem imageItem = new ImageItem();
                            imageItem.setImageFromDB(imageForDb);
                            imageItems.add(imageItem);

                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }
        }, new Response.ErrorListener() {

            @Override
            public void onErrorResponse(VolleyError error) {
            }
        });

        // Adding request to volley request queue
        AppController.getInstance().addToRequestQueue(jsonReq);

        return imageItems;
    }