Android - IF Statement using Spinner while Textview obtained from JSON

i have tried any code tutorial from internet, but i didn't find out any working code to solve my problem,

i wanna try using toast while user choose an item in spinner he/she obtained from this json link

and this is my code i've been tried

private void requestJsonObject(){
        RequestQueue queue = Volley.newRequestQueue(this);
        StringRequest stringRequest = new StringRequest(Request.Method.GET, PATH_TO_SERVER, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                GsonBuilder builder = new GsonBuilder();
                Gson mGson = builder.create();
                spinnerData = Arrays.asList(mGson.fromJson(response, DataObject[].class));
                //display first question to the user
                spinner = (Spinner) findViewById(R.id.spinner);
                assert spinner != null;
                spinner.setVisibility(View.VISIBLE);
                SpinnerAdapter spinnerAdapter = new SpinnerAdapter(MainActivity.this, spinnerData);
                spinner.setAdapter(spinnerAdapter);
                spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                    @Override
                    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                        String Text = parent.getSelectedItem().toString();
                        if(Text.equals("ardi halim")){
                            Toast.makeText(MainActivity.this,"Testing", Toast.LENGTH_LONG).show();
                        }
                        else if(Text.equals("indah")){
                            Toast.makeText(MainActivity.this,"Testing Indah", Toast.LENGTH_LONG).show();
                        }
                    }

why my toast not show in the screen when i tap ardi halim??

did i doing something wrong when i put the code?