android - making a GSON request using volley

Question

I have the following json response

{
  "tag": [
    {
      "listing_count": 5,
      "listings": [
        {
          "source": "source1",
          "data": {
            "image": "image1",
            "name": "name1"
          },
          "name": "name1"
        }
      ]
    },
    {
      "listing_count": 5,
      "listings": [
        {
          "source": "source2",
          "data": {
            "image": "imag2",
            "name": "name2"
          },
          "name": "name2"
        }
      ]
    }
  ]
}

I have created the following classes for GSON request. How do I make the GSON request and store the values for the response using a volley request. What should the GSON request be like?

public class TagList {

ArrayList<Tag> tags;

public static class Tag {
    int listing_count;
    ArrayList<Listings> listings;

    public int getListing_count() {
        return listing_count;
    }

    public void setListing_count(int listing_count) {
        this.listing_count = listing_count;
    }

    public ArrayList<Listings> getListings() {
        return listings;
    }

    public void setListings(ArrayList<Listings> listings) {
        this.listings = listings;
    }

}

public static class Listings {
    String source;
    Data data;
    String name;

    public String getSource() {
        return source;
    }

    public void setSource(String source) {
        this.source = source;
    }

    public Data getData() {
        return data;
    }

    public void setData(Data data) {
        this.data = data;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

public static class Data {
    String image;
    String name;

    public String getImage() {
        return image;
    }

    public void setImage(String image) {
        this.image = image;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

Answer 1

Just create a GsonRequest Class as follows (taken from Android Developer Docs)

public class GsonRequest<T> extends Request<T> {
private final Gson gson = new Gson();
private final Class<T> clazz;
private final Map<String, String> headers;
private final Listener<T> listener;

/**
 * Make a GET request and return a parsed object from JSON.
 *
 * @param url URL of the request to make
 * @param clazz Relevant class object, for Gson's reflection
 * @param headers Map of request headers
 */
public GsonRequest(String url, Class<T> clazz, Map<String, String> headers,
        Listener<T> listener, ErrorListener errorListener) {
    super(Method.GET, url, errorListener);
    this.clazz = clazz;
    this.headers = headers;
    this.listener = listener;
}

@Override
public Map<String, String> getHeaders() throws AuthFailureError {
    return headers != null ? headers : super.getHeaders();
}

@Override
protected void deliverResponse(T response) {
    listener.onResponse(response);
}

@Override
protected Response<T> parseNetworkResponse(NetworkResponse response) {
    try {
        String json = new String(
                response.data,
                HttpHeaderParser.parseCharset(response.headers));
        return Response.success(
                gson.fromJson(json, clazz),
                HttpHeaderParser.parseCacheHeaders(response));
    } catch (UnsupportedEncodingException e) {
        return Response.error(new ParseError(e));
    } catch (JsonSyntaxException e) {
        return Response.error(new ParseError(e));
    }
}
} 

Now in your class file (Activity) just call the this class as follows:

RequestQueue queue = MyVolley.getRequestQueue();
GsonRequest<MyClass> myReq = new GsonRequest<MyClass>(Method.GET,
                                                    "http://JSONURL/",
                                                    TagList.class,
                                                    createMyReqSuccessListener(),
                                                    createMyReqErrorListener());

            queue.add(myReq);

We also need to create two methods -

1. createMyReqSuccessListener() - receive the response from GsonRequest
2. createMyReqErrorListener() - to handle any error

as follows:

private Response.Listener<MyClass> createMyReqSuccessListener() {
    return new Response.Listener<MyClass>() {
        @Override
        public void onResponse(MyClass response) {
           // Do whatever you want to do with response;
           // Like response.tags.getListing_count(); etc. etc.
        }
    };
}

and

private Response.ErrorListener createMyReqErrorListener() {
    return new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            // Do whatever you want to do with error.getMessage();
        }
    };
}

I hope it will make some sense.