How to change response messages?

Question

Android

Hello!
At the moment, if the request is sent, then the server response looks like the content of the html document to which I directly send the request (I don’t need to).
I can’t quite understand what needs to be changed in the code so that the message “Successful” is displayed on a successful operation, and “Error” on any other.

My MainActivity code:

new Response.Listener<String>() {
                            @Override
                            public void onResponse(String response) {
                                Toast.makeText(MainActivity.this, response.trim(), Toast.LENGTH_SHORT).show();
                            }
                        },
                        new Response.ErrorListener() {
                            @Override
                            public void onErrorResponse(VolleyError error) {
                                Toast.makeText(MainActivity.this, error.toString(), Toast.LENGTH_SHORT).show();
                            }
                        }){
                    @Override
                    protected Map<String, String> getParams() {
                        Map<String,String> params = new HashMap<String, String>();
                        params.put("count_id",s);

                        return params;
                    }
                };
                RequestQueue requestQueue = Volley.newRequestQueue(MainActivity.this);
                requestQueue.add(stringRequest);

            }
        });

I will be extremely grateful for any help!