通过截击获得请求发布时的JSON响应

当用户发布现有ticknumber时，我有php文件，php将为发布的一个数组返回JSON代码，我将其与Activity链接，后者将执行相同的php文件工作，但当我单击按钮时，Listview中没有显示任何内容！！

<?php

    if ($_SERVER ['REQUEST_METHOD']=='POST') {
        $ticketnumber = $_POST['ticketnumber'];
        require_once('config.php');
     $con->set_charset('utf8');
        $sql = " SELECT * FROM contact WHERE ticketnumber = '$ticketnumber' ";
        $res = mysqli_query($con, $sql);
         $result = array();
        while($get = mysqli_fetch_array($res))
        {
            array_push($result,array('ticketnumber' =>$get[5], 'subject' =>$get[4],'response' =>$get[6]));
        }
        if(!empty($result)){
            echo json_encode(array("responseticket"=>$result));
        } else {
            echo " error";
        }
}
?>

SupportActivity.java

public class supportActivity extends AppCompatActivity implements View.OnClickListener{
private EditText ticketsupport;
private Button button;
private List<supportContent> con = new ArrayList<supportContent>();
private ListView supportlist;
private supportAdapter adapter;
private String ticketinput;
private String url = "http://10.0.3.2/aaa/getticket.php";
private RequestQueue requestQueue1;
int i ;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_support);
     ticketsupport = (EditText)findViewById(R.id.insertticketnumber);
     supportlist = (ListView)findViewById(R.id.supportlistview);
     adapter = new supportAdapter(this, con);
    supportlist.setAdapter(adapter);
     button = (Button)findViewById(R.id.buttonsupprt);
    button.setOnClickListener(this);

}
private void inquiry() {
         ticketinput = ticketsupport.getText().toString().trim();
    StringRequest stringRequest1 = new StringRequest(Request.Method.POST, url,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    if (response.trim().equals("error")) {
                        Toast.makeText(supportActivity.this, "please check the number", Toast.LENGTH_SHORT).show();
                    } else {

                        try {
                            JSONObject ticket ;
                            JSONArray jsonArray = new JSONArray("responseticket");
                            ticket = jsonArray.getJSONObject(Integer.parseInt(response));
                            supportContent support = new supportContent();
                            support.setTicketnumber(ticket.getString("ticketnumber"));
                            support.setSubject(ticket.getString("subject"));
                            support.setResponse(ticket.getString("response"));
                            con.add(support);

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                        adapter.notifyDataSetChanged();
                    }
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Toast.makeText(supportActivity.this, "something wrong" , Toast.LENGTH_SHORT).show();
        }
    }) {
        @Override
    protected Map<String,String> getParams() throws AuthFailureError{
            Map<String,String> map = new HashMap<String,String>();
            map.put("ticknumber", ticketinput);
            return map;
        }
    };
     requestQueue1 = Volley.newRequestQueue(getApplicationContext());
    requestQueue1.add(stringRequest1);
}
@Override
public void onDestroy(){
    super.onDestroy();
}

@Override
    public void onClick(View view){
        inquiry();
 }
}

SupportAdapter.java

public class supportAdapter extends ArrayAdapter<supportContent> {
private Context context;
private List<supportContent> contents;
public supportAdapter(Context context, List<supportContent> con){
    super(context, R.layout.supportcontent, con);
    this.contents = con;
}
@Override
public int getCount(){
    return contents.size();
}
public View getView(int position, View convertview, ViewGroup parent){
    LayoutInflater inflater = LayoutInflater.from(getContext());
    View supcon = inflater.inflate(R.layout.supportcontent, null);
    TextView ticketnumber = (TextView)supcon.findViewById(R.id.ticketnumber);
    ticketnumber.setText(contents.get(position).getTicketnumber());
    TextView supportsubject = (TextView)supcon.findViewById(R.id.supportsubject);
    supportsubject.setText(contents.get(position).getSubject());
    TextView response = (TextView)supcon.findViewById(R.id.response);
    response.setText(contents.get(position).getResponse());
    return supcon;
}
}