MySQL-PHP-JSON problem

[PaperMexican]

Firstly I want to thank u on tutorial that u made about connecting to phpMyadmin database which helped me alot about certain problems(I'm still in highschool so I don't know much about proggraming in android). And now to my main issue:

> insert.setOnClickListener(new View.OnClickListener() {
>             @Override
>             public void onClick(View view) {
>                 StringRequest request = new StringRequest(Request.Method.POST, insertUrl, new Response.Listener<String>() {
>                     @Override
>                     public void onResponse(String response) {
> 
>                         System.out.println(response.toString());
>                     }
>                 }, new Response.ErrorListener() {
>                     @Override
>                     public void onErrorResponse(VolleyError error) {
> 
>                     }
>                 }) {
> 
>                     @Override
>                     protected Map<String, String> getParams() throws AuthFailureError {
>                         Map<String,String> parameters  = new HashMap<String, String>();
>                         parameters.put("firstname",firstname.getText().toString());
>                         parameters.put("lastname",lastname.getText().toString());
>                         parameters.put("age",age.getText().toString());
> 
>                         return parameters;
>                     }
>                 };
>                 requestQueue.add(request);
>             }
> 
>         });
> 
> 
>     }
> 
> }

it shows me:
"Program type already present: com.android.volley.NetworkDispatcher
Message{kind=ERROR, text=Program type already present: com.android.volley.NetworkDispatcher, sources=[Unknown source file], tool name=Optional.of(D8)}"