Volley requests get overlap

Question

So i had this add to cart view : < 1 >. What i want is when press ">" the system will check if user already had a cart, if not, create one, then proceed to add the product to cart. I made two functions to do this: createCart() and addProductFirstTime(). But somehow they got "mixed" with each other, for example, i have a Log.d("Create cart") in createCart() and Log.d("Add product first time") in addProductFirstTime(). And when i ran it, the "create cart" in the place where "add product first time" should be . To summarize, some proceed should be performed in createCart() appear in addProductFirstTime() and vice versa. Can someone please tell me what is going on? I very appreciate it.

This is how i called createCart() and addProductFirstTime():

if(user.getIsAddFirstTime()==0){
                user.setIsAddFirstTime(1);
                createCart();
                
            } 
addProductFirstTime();

My function addProductFirstTime():

  public void addProductFirstTime(){
            Log.d("Info", "add first time");

            StringRequest stringRequest = new StringRequest(Request.Method.POST, URL_ADD_FIRST_TIME, new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    Log.d("Info:", "Still in add first time");
                    try {
                    //   Log.d("addfirsttimerespond is:", response + "Hello");
                        Log.d("addfirsttimecartid: ", Integer.toString(SharePrefManager.getInstance(mcontext).getCartid()));
                            JSONObject jsonObject = new JSONObject(response);
                     //   Toast.makeText(mcontext, jsonObject.getString("message"), Toast.LENGTH_LONG).show();
                      // cart.setCartId(jsonObject.getInt("cartid"));
                         Log.d("addfirsttimecartid: ", Integer.toString(SharePrefManager.getInstance(mcontext).getCartid()));

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Toast.makeText(mcontext, error.getMessage(),Toast.LENGTH_LONG).show();
                }
            }){
       
                @Nullable
                @Override
                protected Map<String, String> getParams() throws AuthFailureError {
                    Map<String, String> params = new HashMap<>();
                    params.put("productid", Integer.toString(productVariation.getId()));
                    params.put("price", Integer.toString(productVariation.getPrice()));
                    params.put("quantity", Integer.toString(productVariation.getQuantity()));
                    params.put("cartid", Integer.toString(SharePrefManager.getInstance(mcontext).getCartid()));

                    Log.d("Info","add product first time again");
                    //Log.d
                    return params;
                }
            };
            requestHandler.getInstance(mcontext).addToRequestQueue(stringRequest);
          // Volley.newRequestQueue(mcontext).add(stringRequest);
           // requestQueue.add(stringRequest);
            Log.d("mycartid: ",Integer.toString(SharePrefManager.getInstance(mcontext).getCartid()) );
        }

My function createCart():

public void createCart(){
            n++;
            Log.d("n=", Integer.toString(n));
            Log.d("Info", "Create cart");
            StringRequest stringRequest = new StringRequest(Request.Method.POST, URL_CREATE_CART, new Response.Listener<String>() {

                @Override

                public void onResponse(String response) {

                    try {
                        Log.d("Info:", "Still in create cart");
                        JSONObject jsonObject = new JSONObject(response);
                        SharePrefManager.getInstance(mcontext).setCartId(jsonObject.getInt("cartid"));
                     //   cart.setCartId(jsonObject.getInt("cartid"));
                        Log.d("create cart id is:", Integer.toString( SharePrefManager.getInstance(mcontext).getCartid()));
                        // Toast.makeText(mcontext, jsonObject.getInt("cartid"), Toast.LENGTH_LONG).show();
                     //   Log.d("cart id is:" , Integer.toString(jsonObject.getInt("cartid")));



                        //   Log.d("cartid: ", Integer.toString(cart.getCartId()));

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

                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Toast.makeText(mcontext, error.getMessage(),Toast.LENGTH_LONG).show();
                }
            }){
                @Nullable
                @Override
                protected Map<String, String> getParams() throws AuthFailureError {
                    Map<String, String> params = new HashMap<>();
                    params.put("userid", Integer.toString(user.getId()));
                    Log.d("Info","Create cart again");
                    Log.d("Info", "trang thai tao gio hang: "+ Integer.toString(user.getIsAddFirstTime()));
                    return params;

                }
            };
           // Volley.newRequestQueue(mcontext).add(stringRequest);
            requestHandler.getInstance(mcontext).addToRequestQueue(stringRequest);
            //requestQueue.add(stringRequest);
        }

This is what i got in the console:

D/Info: Create cart
D/Info: add first time
D/mycartid:: 90
D/Info: Create cart again
D/Info: trang thai tao gio hang: 1
D/Info: add product first time again
D/Info:: Still in add first time
D/addfirsttimecartid:: 90
//// a bunch of errors, they belong to addProductFirstTime() btw
D/Info:: Still in create cart
D/create cart id is:: 91