java - Android - Arraylist 在 for 循环外返回 null

Question

我得到了 List<String> resultList ResponseFinal 日志中的响应为空。但在循环内，响应显示 resultList

中的项目

我不明白为什么结果列表在循环外返回空。请帮忙

public List<String> getParseJson(String sName)
{
    final List<String> resultList = new ArrayList<String>();

    String name=sName.replace(" ", "%20");
    StringRequest stringRequest = new StringRequest(Request.Method.GET, Constants.BASE_URL + "/suggest_item/items/"+name +"/"+ Constants.API_KEY,
        new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                // Result handling
                try {
                    JSONObject jsonObj = new JSONObject(response.toString());
                    JSONArray predsJsonArray = jsonObj.getJSONArray("Item");

                    for (int i = 0; i < predsJsonArray.length(); i++) {
                        System.out.println( predsJsonArray.get(i).toString());
                        resultList.add(predsJsonArray.get(i).toString());
                        Log.e("Response",resultList.toString());
                    }
                } catch (JSONException e) {
                    Log.e("JSOn", "Cannot process JSON results", e);
                }
           }
      }, new Response.ErrorListener() {
           @Override
           public void onErrorResponse(VolleyError error) {
                // Error handling
                System.out.println(error.toString());

           }
     });

     // Adding request to request queue
     Volley.newRequestQueue(context).add(stringRequest);

     Log.e("ResponseFinal",resultList.toString());
     return resultList;
}

我的日志:

E/Response: [1660309, 1660410]
E/ResponseFinal: []

Answer 1

在 oncreate() 之前声明 List(在类级别定义 resultList)

List<String> resultList = new ArrayList<String>();