How to make separate class for volley library and call all method of volley from another activity and get response?

First create callback interface to get result in Activity

public interface IResult {
    public void notifySuccess(String requestType,JSONObject response);
    public void notifyError(String requestType,VolleyError error);
}

Create a separate class with volley function to response the result through interface to activity

public class VolleyService {

    IResult mResultCallback = null;
    Context mContext;

    VolleyService(IResult resultCallback, Context context){
        mResultCallback = resultCallback;
        mContext = context;
    }


    public void postDataVolley(final String requestType, String url,JSONObject sendObj){
        try {
            RequestQueue queue = Volley.newRequestQueue(mContext);

            JsonObjectRequest jsonObj = new JsonObjectRequest(url,sendObj, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    if(mResultCallback != null)
                        mResultCallback.notifySuccess(requestType,response);
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    if(mResultCallback != null)
                        mResultCallback.notifyError(requestType,error);
                }
            });

            queue.add(jsonObj);

        }catch(Exception e){

        }
    }

    public void getDataVolley(final String requestType, String url){
        try {
            RequestQueue queue = Volley.newRequestQueue(mContext);

            JsonObjectRequest jsonObj = new JsonObjectRequest(Request.Method.GET, url, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    if(mResultCallback != null)
                        mResultCallback.notifySuccess(requestType, response);
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    if(mResultCallback != null)
                        mResultCallback.notifyError(requestType, error);
                }
            });

            queue.add(jsonObj);

        }catch(Exception e){

        }
    }
} 

Then initialize callback interface into main activity

    mResultCallback = new IResult() {
        @Override
        public void notifySuccess(String requestType,JSONObject response) {
            Log.d(TAG, "Volley requester " + requestType);
            Log.d(TAG, "Volley JSON post" + response);
        }

        @Override
        public void notifyError(String requestType,VolleyError error) {
            Log.d(TAG, "Volley requester " + requestType);
            Log.d(TAG, "Volley JSON post" + "That didn't work!");
        }
    };

Now create object of VolleyService class and pass it context and callback interface

mVolleyService = new VolleyService(mResultCallback,this);

Now call the Volley method for post or get data also pass requestType which is to identify the service requester when getting result back into main activity

    mVolleyService.getDataVolley("GETCALL","http://192.168.1.150/datatest/get/data");
    JSONObject sendObj = null;

    try {
        sendObj = new JSONObject("{'Test':'Test'}");
    } catch (JSONException e) {
        e.printStackTrace();
    }
    mVolleyService.postDataVolley("POSTCALL", "http://192.168.1.150/datatest/post/data", sendObj);

Final MainActivity

public class MainActivity extends AppCompatActivity {
    private String TAG = "MainActivity";
    IResult mResultCallback = null;
    VolleyService mVolleyService;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initVolleyCallback();
        mVolleyService = new VolleyService(mResultCallback,this);
        mVolleyService.getDataVolley("GETCALL","http://192.168.1.150/datatest/get/data");
        JSONObject sendObj = null;

        try {
            sendObj = new JSONObject("{'Test':'Test'}");
        } catch (JSONException e) {
            e.printStackTrace();
        }
        mVolleyService.postDataVolley("POSTCALL", "http://192.168.1.150/datatest/post/data", sendObj);
    }

    void initVolleyCallback(){
        mResultCallback = new IResult() {
            @Override
            public void notifySuccess(String requestType,JSONObject response) {
                Log.d(TAG, "Volley requester " + requestType);
                Log.d(TAG, "Volley JSON post" + response);
            }

            @Override
            public void notifyError(String requestType,VolleyError error) {
                Log.d(TAG, "Volley requester " + requestType);
                Log.d(TAG, "Volley JSON post" + "That didn't work!");
            }
        };
    }

}

Find the whole project at following link

https://github.com/PatilRohit/VolleyCallback