<?php
  $con = mysqli_connect("my_host", "my_user", "my_password", "my_database");

$username = $_POST["username"];
$password = $_POST["password"];

$statement = mysqli_prepare($con, "SELECT * FROM user WHERE username = ? AND password = ?");
mysqli_stmt_bind_param($statement, "ss", $username, $password);
mysqli_stmt_execute($statement);

mysqli_stmt_store_result($statement);
mysqli_stmt_bind_result($statement, $userID, $name, $username, $password);

$response = array();
$response["success"] = false;

while(mysqli_stmt_fetch($statement)){
    $response["success"] = true;
    $response["name"] = $name;
    $response["username"] = $username;
    $response["password"] = $password;
}

echo json_encode($response);
?>

public void onResponse(String response) {
                    try {
                        JSONObject jsonResponse = new JSONObject(response);
                        boolean success = jsonResponse.getBoolean("success");

                        if (success) {
                            String name = jsonResponse.getString("name");

                            Intent intent = new Intent(LoginActivity.this, WelcomeActivity.class);
                            intent.putExtra("name", name);
                            intent.putExtra("username", username);
                            LoginActivity.this.startActivity(intent);
                        } else {
                            AlertDialog.Builder builder = new AlertDialog.Builder(LoginActivity.this);
                            builder.setMessage("Login Failed")
                                    .setNegativeButton("Retry", null)
                                    .create()
                                    .show();
                        }

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            };

            LoginRequest loginRequest = new LoginRequest(username, password, responseListener);
            RequestQueue queue = Volley.newRequestQueue(LoginActivity.this);
            queue.add(loginRequest);
        }

07-18 15:58:34.729 29396-29402/com.example.arthurf.tcc.app W/art: Suspending all threads took: 10.852ms
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err: org.json.JSONException: Value <br><table of type java.lang.String cannot be converted to JSONObject
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at org.json.JSON.typeMismatch(JSON.java:111)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at org.json.JSONObject.<init>(JSONObject.java:160)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at org.json.JSONObject.<init>(JSONObject.java:173)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at com.example.arthurf.tcc.app.LoginActivity$1$1.onResponse(LoginActivity.java:40)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at com.example.arthurf.tcc.app.LoginActivity$1$1.onResponse(LoginActivity.java:36)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:60)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at android.os.Handler.handleCallback(Handler.java:739)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:95)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at android.os.Looper.loop(Looper.java:148)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5417)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
07-18 15:58:34.887 29396-29396/com.example.arthurf.tcc.app W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)