Cannot retrieve the JSON format data from php to android studio : It is a register function . I am able to add record to my database. But for the  response made through the php script, I cannot show the response or get the response from the php to the andriod studio....

when the email is duplicated, the php should response a fail.... how could I get it show in android stuido 

Any help please@@@@@



register.php

    <?php
    include_once 'connection.php';

    class User {

    private $db;
    private $connection;

    function __construct() {
        $this -> db = new DB_Connection();
        $this -> connection = $this->db->getConnection();
    }

    public function does_user_exist($name,$tel_no,$contact_point,$email,$address,$logo_url, $operation_time,$encrypted_password)
    {
        $query = "Select * from shop where email='$email'  ";
        $result = mysqli_query($this->connection, $query);
        if(mysqli_num_rows($result)>0){
            $json['fail'] = ' Already registered '.$email;
            echo json_encode($json);
            mysqli_close($this -> connection);
        }else{
            $query = "insert into shop (name, tel_no, contact_point, email, address, logo_url, operation_time, password) values ( '$name','$tel_no','$contact_point','$email','$address','$logo_url','$operation_time','$encrypted_password')";
            $inserted = mysqli_query($this -> connection, $query);
            if($inserted == 1 ){
                $json['success'] = 'Account created';
            }else{
                $json['error'] = 'Wrong password';
            }
            echo json_encode($json);
            mysqli_close($this->connection);
        }

    }

     }


    $user = new User();

     ..........


Register.java



     public class Register extends AppCompatActivity {private EditText nam, teln, 
     contactpoin, emai, addres, logour, operationtim, pw1 , pw2;
    private Button btnregister;
    private RequestQueue requestQueue;
    private static final String Url  = "http://XXXXXX/stampe/register.php";
    private StringRequest request;

    @Override
    protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);

        StrictMode.ThreadPolicy threadPolicy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(threadPolicy);

        ActionBar actionBar = getSupportActionBar();
        actionBar.hide();


        nam = (EditText) findViewById(R.id.name);
        teln = (EditText) findViewById(R.id.tel_no);
        contactpoin = (EditText) findViewById(R.id.contact_point);
        emai = (EditText) findViewById(R.id.email);
        addres = (EditText) findViewById(R.id.address);
        logour = (EditText) findViewById(R.id.logo_url);
        operationtim = (EditText) findViewById(R.id. operation_time);
        pw1 = (EditText) findViewById(R.id. password);
        pw2 = (EditText) findViewById(R.id. pwcheck);
        btnregister = (Button) findViewById(R.id.btn_register);

        requestQueue = Volley.newRequestQueue(this);


        btnregister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if(nam.getText().length()==0 ||teln.getText().length()==0 ||contactpoin.getText().length()==0 ||emai.getText().length()==0 ||pw1.getText().length()==0 ||pw2.getText().length()==0   )
                {
                    btnregister.setError("請輸入資料!");
                }else if(!pw1.getText().toString().equals(pw2.getText().toString())){
                    System.out.println(pw1.getText().toString());
                    System.out.println(pw2.getText().toString());
                    pw1.setError("兩次輸入的密碼不一致");
                }
                else{

                request = new StringRequest(Request.Method.POST, Url, new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {

                        try {
                            JSONObject jsonObject = new JSONObject(response);
                            System.out.print(jsonObject);
                            if(jsonObject.names().get(0).equals("success")){
                                Toast.makeText(getApplicationContext(),"SUCCESS "+jsonObject.getString("success"),Toast.LENGTH_SHORT).show();
                                startActivity(new Intent(getApplicationContext(),MainActivity.class));
                            }else {
                                Toast.makeText(getApplicationContext(), "Error" +jsonObject.getString("error"), Toast.LENGTH_SHORT).show();
                            }

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                                startActivity(new Intent(getApplicationContext(),MainActivity.class));
                    }
                }, new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                    }
                }){



                    @Override
                    protected Map<String, String> getParams() throws AuthFailureError {
                       HashMap<String,String> hashMap = new HashMap<String, String>();

                        hashMap.put("name",nam.getText().toString());
                        hashMap.put("tel_no",teln.getText().toString());
                        hashMap.put("contact_point",contactpoin.getText().toString());
                        hashMap.put("email",emai.getText().toString());
                        hashMap.put("address",addres.getText().toString());
                        hashMap.put("logourl",logour.getText().toString());
                        hashMap.put("operation_time",operationtim.getText().toString());
                        hashMap.put("password",pw1.getText().toString());
                        return hashMap;
                    }
                };requestQueue.add(request); }}});}}





