Cannot assign value to final Volley variable response

Question

I am familiar with Volley and creating a Singleton class, and adding requests to the queue. However, I wish to increase the modularity of volley and simply call all requests through method call to another class instead. I have setup the present action as basis for the common GET request:

public Object getRequest(String params) {

    final JSONObject getRequestReturn = new JSONObject();

    JsonObjectRequest getRequest = new JsonObjectRequest(Request.Method.GET,
            VolleySingleton.prefixURL, ((String) null),
            new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {

                    // Parse the JSON:
                    try {
                        getRequestReturn = response;

                        Log.v("GET Request value", response.toString());

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

                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d("GET Request Error", error.toString());
                }
            });

    mRequestQueue.add(getRequest);

    return getRequestReturn;
}

However, I have a the perplexing catch 22 error on the assignment of response at:

getRequestReturn = response;

The error notes that getRequestReturn must be declared final to allow for use within the inner class, but upon assigning final, another error appears noting that you cannot assign a value to a final variable.

How can this method be handled?

Don't use return like that, you won't get anything, please take a look at my answer at the following question http://stackoverflow.com/questions/32627089/post-request-json-file-passing-string-and-wait-for-the-response-volley/32627293#32627293 — BNK, Nov 04 '15 at 12:59
Another one http://stackoverflow.com/questions/32375295/android-how-to-return-async-jsonobject-from-method-using-volley :) — BNK, Nov 04 '15 at 13:05
@BNK How about: http://stackoverflow.com/questions/19837820/volley-jsonobjectrequest-post-request-not-working, looks very concise, and the call is very clean as simply: `RequestQueue requestQueue = Volley.newRequestQueue(getActivity()); CustomRequest jsObjRequest = new CustomRequest(Method.POST, url, params, this.createRequestSuccessListener(), this.createRequestErrorListener()); requestQueue.add(jsObjRequest);` — Sauron, Nov 04 '15 at 21:21
@Sauron: it's OK, sure, however, I just mean if you move these lines into a method/funtion, then return at the end of that method, you won't get anything (null) with that return value. I will give you another link for your reference :) — BNK, Nov 04 '15 at 22:18
@Sauron: please read my question before http://stackoverflow.com/questions/31602042/android-java-how-to-delay-return-in-a-method, you should read all answers there :), hope it helps! — BNK, Nov 04 '15 at 22:20
@Sauron: if you just ask about final variable, you should only change its scope (declaration). I only tell you about the `return getRequestReturn;`, it means when you call `abc = getRequest(...);` somewhere, you will always get an empty jsonobject — BNK, Nov 05 '15 at 01:32

score 0 · Answer 1 · edited Nov 04 '15 at 12:51

0

Declare JSONObject as global and initialize in same place like this.

 JSONObject getRequestReturn ;


getRequestReturn = new JSONObject();

edited Nov 04 '15 at 12:51

Abhinav singh

1,448
1
14
31

answered Nov 04 '15 at 12:46

d.k.

415
4
16

tiny sunlight · Answer 2 · 2015-11-04T16:05:33.057

public Object getRequest(String params) {

    JsonObjectRequest getRequest = new JsonObjectRequest(Request.Method.GET,
            VolleySingleton.prefixURL, ((String) null),
            new Response.Listener<JSONObject>() {
                @Override 
                public void onResponse(JSONObject response) {

                    // Parse the JSON: 
                    try { 

                        Log.v("GET Request value", response.toString());

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

                } 
            }, 
            new Response.ErrorListener() {
                @Override 
                public void onErrorResponse(VolleyError error) {
                    Log.d("GET Request Error", error.toString());
                } 
            }); 

    mRequestQueue.add(getRequest);

    return new JSONObject();
}

U can't get response when u return!Volley request is async!

I use EventBus and I do it like this ：

When I need to get data from web , i add a request like this.

Then when i get response from web ,I use EventBus to post a event.

I get the event and update my page.

Or U can try the RxAndroid.

This will not output anything as it is simply returning an new JSON Object...not the result of the network operation output — Sauron, Nov 04 '15 at 15:12
@Sauron: Tiny sunlight is right, you can refer 2 links I commented above. — BNK, Nov 04 '15 at 15:24
@BNK you can provide an answer, as tiny sunlight borders on offensive — Sauron, Nov 04 '15 at 15:30
@Sauron: I'll post my answer tomorrow. I am on mobile now, it's difficult to format the code. — BNK, Nov 04 '15 at 15:42

Cannot assign value to final Volley variable response

2 Answers2