org.json.JSONException value type java.lang.String cannot be converted to JSONObject

Question

I'm trying to make a login/register app and when i run the code i get this error and my code doesn't work. What am i doing wrong? how can i solve this? If additional code is needed i can provide. Also if this question has a response already can you guide me to that response? I'm trying to find a solution to this problem since 2 days ago and can't seem to find what the problem is. I'm quite new to coding so any help is welcomed.

db_connect.php

<?php
define('DB_USER', "root"); // db user
define('DB_PASSWORD', ""); // db password (mention your db password here)
define('DB_DATABASE', "member"); // database name
define('DB_SERVER', "localhost"); // db server

$con = mysqli_connect(DB_SERVER,DB_USER,DB_PASSWORD,DB_DATABASE);

// Check connection
if(mysqli_connect_errno())
{
 echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

?>

Function.php

<?php
$random_salt_length = 32;
/**
* Queries the database and checks whether the user already exists
* 
* @param $username
* 
* @return
*/
function userExists($username){
 $query = "SELECT username FROM member WHERE username = ?";
 global $con;
 if($stmt = $con->prepare($query)){
 $stmt->bind_param("s",$username);
 $stmt->execute();
 $stmt->store_result();
 $stmt->fetch();
 if($stmt->num_rows == 1){
 $stmt->close();
 return true;
 }
 $stmt->close();
 }

 return false;
}

function concatPasswordWithSalt($password,$salt){
 global $random_salt_length;
 if($random_salt_length % 2 == 0){
 $mid = $random_salt_length / 2;
 }
 else{
 $mid = ($random_salt_length - 1) / 2;
 }

 return
 substr($salt,0,$mid - 1).$password.substr($salt,$mid,$random_salt_length - 1);

}
?>

Login.php

<?php
$response = array();
include 'db/db_connect.php';
include 'functions.php';
//Get the input request parameters
$inputJSON = file_get_contents('php://input');
$input = json_decode($inputJSON); //convert JSON into array
//Check for Mandatory parameters
if(isset($input->username) && isset($input->password)){
$username = $input->username;
$password = $input->password;
$query    = "SELECT full_name,password_hash, salt FROM member WHERE username = ?";
if($stmt = $con->prepare($query)){
$stmt->bind_param("s",$username);
$stmt->execute();
$stmt->bind_result($fullName,$passwordHashDB,$salt);
if($stmt->fetch()){
//Validate the password
if(password_verify(concatPasswordWithSalt($password,$salt),$passwordHashDB)){
$response["status"] = 0;
$response["message"] = "Login successful";
$response["full_name"] = $fullName;
}
else{
$response["status"] = 1;
$response["message"] = "Invalid username and password combination";
}
}
else{
$response["status"] = 1;
$response["message"] = "Invalid username and password combination";
}
$stmt->close();
}
}
else{
$response["status"] = 2;
$response["message"] = "Missing mandatory parameters";
}
//Display the JSON response
echo json_encode($response);
?>

Register.php

<?php
$response = array();
include 'db/db_connect.php';
include 'Functions.php';
//Get the input request parameters
$inputJSON = file_get_contents('php://input');
$input = json_decode($inputJSON, TRUE); //convert JSON into array
//Check for Mandatory parameters
if(isset($input['username']) && isset($input['password']) && isset($input['full_name'])){
$username = $input['username'];
$password = $input['password'];
$fullName = $input['full_name'];
//Check if user already exist
if(!userExists($username)){
//Get a unique Salt
$salt         = getSalt();
//Generate a unique password Hash
$passwordHash = password_hash(concatPasswordWithSalt($password,$salt),PASSWORD_DEFAULT);
//Query to register new user
$insertQuery  = "INSERT INTO member(username, full_name, password_hash, salt) VALUES (?,?,?,?)";
if($stmt = $con->prepare($insertQuery)){
$stmt->bind_param("ssss",$username,$fullName,$passwordHash,$salt);
$stmt->execute();
$response["status"] = 0;
$response["message"] = "User created";
$stmt->close();
}
}
else{
$response["status"] = 1;
$response["message"] = "User exists";
}
}
else{
$response["status"] = 2;
$response["message"] = "Missing mandatory parameters";
}
echo json_encode($response);
?>

RegisterActivity.java

package com.example.activitymanagement;

import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;

import org.json.JSONException;
import org.json.JSONObject;

public class RegisterActivity extends AppCompatActivity {
    private static final String KEY_STATUS = "status";
    private static final String KEY_MESSAGE = "message";
    private static final String KEY_FULL_NAME = "full_name";
    private static final String KEY_USERNAME = "username";
    private static final String KEY_PASSWORD = "password";
    private static final String KEY_EMPTY = "";
    private EditText etUsername;
    private EditText etPassword;
    private EditText etConfirmPassword;
    private EditText etFullName;
    private String username;
    private String password;
    private String confirmPassword;
    private String fullName;
    private ProgressDialog pDialog;
    private String register_url = "http://10.0.2.2/member/register.php";
    private SessionHandler session;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        session = new SessionHandler(getApplicationContext());
        setContentView(R.layout.activity_register);

        etUsername = findViewById(R.id.etUsername);
        etPassword = findViewById(R.id.etPassword);
        etConfirmPassword = findViewById(R.id.etConfirmPassword);
        etFullName = findViewById(R.id.etFullName);

        Button login = findViewById(R.id.btnRegisterLogin);
        Button register = findViewById(R.id.btnRegister);

        //Launch Login screen when Login Button is clicked
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(RegisterActivity.this, LoginActivity.class);
                startActivity(i);
                finish();
            }
        });

        register.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //Retrieve the data entered in the edit texts
                username = etUsername.getText().toString().toLowerCase().trim();
                password = etPassword.getText().toString().trim();
                confirmPassword = etConfirmPassword.getText().toString().trim();
                fullName = etFullName.getText().toString().trim();
                if (validateInputs()) {
                    registerUser();
                }

            }
        });

    }

    /**
     * Display Progress bar while registering
     */
    private void displayLoader() {
        pDialog = new ProgressDialog(RegisterActivity.this);
        pDialog.setMessage("Signing Up.. Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show();

    }

    /**
     * Launch Dashboard Activity on Successful Sign Up
     */
    private void loadDashboard() {
        Intent i = new Intent(getApplicationContext(), DashboardActivity.class);
        startActivity(i);
        finish();

    }

    private void registerUser() {
        displayLoader();
        JSONObject request = new JSONObject();
        try {
            //Populate the request parameters
            request.put(KEY_USERNAME, username);
            request.put(KEY_PASSWORD, password);
            request.put(KEY_FULL_NAME, fullName);

        } catch (JSONException e) {
            e.printStackTrace();
        }
        JsonObjectRequest jsArrayRequest = new JsonObjectRequest
                (Request.Method.POST, register_url, request, new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {
                        pDialog.dismiss();
                        try {
                            //Check if user got registered successfully
                            if (response.getInt(KEY_STATUS) == 0) {
                                //Set the user session
                                session.loginUser(username,fullName);
                                loadDashboard();

                            }else if(response.getInt(KEY_STATUS) == 1){
                                //Display error message if username is already existsing
                                etUsername.setError("Username already taken!");
                                etUsername.requestFocus();

                            }else{
                                Toast.makeText(getApplicationContext(),
                                        response.getString(KEY_MESSAGE), Toast.LENGTH_SHORT).show();

                            }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                }, new Response.ErrorListener() {

                    @Override
                    public void onErrorResponse(VolleyError error) {
                        pDialog.dismiss();

                        //Display error message whenever an error occurs
                        Toast.makeText(getApplicationContext(),
                                error.getMessage(), Toast.LENGTH_SHORT).show();

                    }
                });

        // Access the RequestQueue through your singleton class.
        MySingleton.getInstance(this).addToRequestQueue(jsArrayRequest);
    }

    /**
     * Validates inputs and shows error if any
     * @return
     */
    private boolean validateInputs() {
        if (KEY_EMPTY.equals(fullName)) {
            etFullName.setError("Full Name cannot be empty");
            etFullName.requestFocus();
            return false;

        }
        if (KEY_EMPTY.equals(username)) {
            etUsername.setError("Username cannot be empty");
            etUsername.requestFocus();
            return false;
        }
        if (KEY_EMPTY.equals(password)) {
            etPassword.setError("Password cannot be empty");
            etPassword.requestFocus();
            return false;
        }

        if (KEY_EMPTY.equals(confirmPassword)) {
            etConfirmPassword.setError("Confirm Password cannot be empty");
            etConfirmPassword.requestFocus();
            return false;
        }
        if (!password.equals(confirmPassword)) {
            etConfirmPassword.setError("Password and Confirm Password does not match");
            etConfirmPassword.requestFocus();
            return false;
        }

        return true;
    }
}

Dharmender Manral · Accepted Answer · 2019-05-27 19:49:38Z

0

please change below line in your php script for getting request params, because you are sending request param inside json object and getting in string format

 $input = json_decode($inputJSON);
 if(isset($input->username) && isset($input->password) && isset($input->full_name)){
$username = $input->username;
$password = $input->password;
$fullName = $input->full_name;
}

edited May 27, 2019 at 19:49

answered May 27, 2019 at 19:12

Dharmender Manral

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3 Comments

Dharmender Manral Over a year ago

Can you share your all php files

Just Me Over a year ago

added all php files in the main question

Dharmender Manral Over a year ago

can you describe what is $salt = getSalt(); because throw exception, Call to undefined function getSalt() in

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