JSON GET请求上的java.lang.NullPointerException

Question

我试图发送一个GET请求，传递一个身份验证令牌头以获取一些JSON数据，但是我得到了所有的java.lang.NullPointerExceptions。我已经尝试使用JSONObjectRequest、JSONArrayRequest甚至StringRequest。

下面是代码（JSONObjectRequest和JSONArrayRequest对测试进行了注释）：

 public void getJSON() {

    final String authToken = getAuth();
    String novaURL = getNova();
    novaURL = novaURL+"/servers";


    /**
___________________________________________________________________
    JsonArrayRequest getRequest = new JsonArrayRequest(novaURL,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    Log.d("Nova", response.toString());
                    setNovaJSON(response.toString());
                }
            }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
            VolleyLog.d("Nova", "Error: " + error.getMessage());
            }
    }
    ){
        public Map<String, String> getHeaders() throws AuthFailureError {
            Map<String, String> params = new HashMap<String, String>();
            params.put("X-Auth-Token", authToken);
            params.put("Accept", "application/json");
            params.put("Content-Type", "application/json; charset=utf-8");
            return params;
        }
    };


    RequestQueue queue = Volley.newRequestQueue(this);
    queue.add(getRequest);

}

    JsonObjectRequest getRequest = new JsonObjectRequest(Request.Method.GET, novaURL, null,
            new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    try {
                        JSONArray servers = response.getJSONArray("servers");
                    } catch (JSONException e) {
                        Toast.makeText(getApplicationContext(), "Error to get Instances", Toast.LENGTH_LONG).show();
                        e.printStackTrace();
                    }

                    Log.d("Nova", response.toString());
                    setNovaJSON(response.toString());
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    VolleyLog.d("Nova", "Error: " + error.getMessage());

                }
            }
    ) {
        public Map<String, String> getHeaders() throws AuthFailureError {
            Map<String, String> params = new HashMap<String, String>();
            params.put("X-Auth-Token", authToken);
            params.put("Accept", "application/json");
            params.put("Content-Type", "application/json; charset=utf-8");
            return params;
        }

    };
 ________________________________________________________________ **/

    StringRequest getRequest = new StringRequest(Request.Method.GET,
            novaURL, new Response.Listener<String>() {

        @Override
        public void onResponse(String response) {
            Log.d("Nova", response.toString());
            setNovaJSON(response.toString());


        }
    }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
            VolleyLog.d("Nova", "Error: " + error.getMessage());
        }
    }) {
        public Map<String, String> getHeaders() throws AuthFailureError {
            Map<String, String> params = new HashMap<String, String>();
            params.put("X-Auth-Token", authToken);
            params.put("Accept", "application/json");
            params.put("Content-Type", "application/json; charset=utf-8");
            return params;
        }
    };

    RequestQueue queue = Volley.newRequestQueue(this);
    queue.add(getRequest);

}

RequestQueue queue = Volley.newRequestQueue(this);

我可能找到了有用的东西。我移动了行“requestqueue queue=volley.newrequestqueue（this）；”在方法的顶部，使用其他变量声明，并且在调试之后，它似乎在到达JSONObjectRequest或StringRequest命令之前就崩溃了。好像排队有问题。

**更新2：

我按照以下步骤修复了队列问题：https://developer.android.com/training/volley/requestqueue.html

java.lang.NullPointerException
        at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
        at org.json.JSONTokener.nextValue(JSONTokener.java:94)
        at org.json.JSONObject.<init>(JSONObject.java:155)
        at org.json.JSONObject.<init>(JSONObject.java:172)

Answer 1

似乎volley.NewRequestQueue（this）的“this”是null。