Question

Create a class called Login which contains a HashMap as a private attribute. It should also have an instance method called loadCredentials which acccepts the two arrays. It will load the Hash Map with key/value pairs based on the two arrays above. The userNames should be the keys and the passwords the values. private static String[] userNameArray = {"John", "Steve", "Bonnie", "Kylie", "Logan", "Robert"); private static String) passwordArray = {"1111", "2222", "3333", "4444", "5555", "6666"}; Create a login method in the Login class. This method will prompt the user for a username and password. It will then return true or false based on whether or not the user enters valid username and password. Note that the username should exist and the password associated with that username should match what is stored for that username in the hashmap. When the flower shop application starts. Call the method to ensure the credentials are loaded. Then continually prompt the user to login until they enter a valid username and password. Provide an error message if login fails. Once a valid username and password is entered the main menu is shown to the user and the program runs normally.

Answer 1

Answer:

Please find the code below, also go through the comments provided to make the code readable. I am enclosing the screenshots of execution of the program with 3 different cases.

• Invalid username
• Valid username and invalid password
• Valid username and password

Valid username and invalid password

Run: Login x /usr/lib/jvm/java-8-oracle/bin/java ... Please enter the username : Bonnie Please enter the password : 1111 The PASSWORD did not match : EL Process finished with exit code o FJI < - I

Valid username and password

Run: Login /usr/lib/jvm/java-8-oracle/bin/java ... Please enter the username : Bonnie Please enter the password : 3333 Thank you, credentials matched : If I Process finished with exit code o

Invalid username

Run: Login /usr/lib/jvm/java-8-oracle/bin/java ... Please enter the username : stranger Please enter the password : 1234 The USER doesn't exist - IR 710 11 Process finished with exit code o I

import java.util.HashMap;
import java.util.Scanner;

public class Login {

    // Class attributes a Hashmap & 2 String arrays
    private HashMap<String, String> credentials = new HashMap<>();
    private static String [] userNameArray = { "John", "Steve", "Bonnie", "Kylie", "Logan", "Robert"};
    private static String [] passwordArray = { "1111", "2222", "3333", "4444", "5555", "6666"};

    // Getters for 2 arrays
    public static String[] getUserNameArray() {
        return userNameArray;
    }

    public static String[] getPasswordArray() {
        return passwordArray;
    }

    // This method loads the HashMap with username and password
    public void loadCredentials(String [] userName, String [] password){
        for (int i=0; i<userName.length; i++){
            credentials.put(userName[i],password[i]);
        }
    }

    /*  This method verifies the username and password
        If the username entered by user doesn't exists then an error message is thrown
        If the username entered by the user exists but password entered doesn't match, then error is thrown to the user
     */
    public void login(){
        String userName, passWord;

        // Ask the user for username
        System.out.println("Please enter the username : ");
        Scanner sc1 = new Scanner(System.in);
        userName = sc1.nextLine();

        // Ask the user for password
        System.out.println("Please enter the password : ");
        Scanner sc2 = new Scanner(System.in);
        passWord = sc2.nextLine();

        // Verify whether the username entered by the user exists in the hashmap
        if (credentials.containsKey(userName)){

            // get the corresponding password for the username entered by the user
            String correspondingPwd = credentials.get(userName); // gets the password for the username

            // Verify whether the username matches with the password
            if (credentials.containsKey(userName) && correspondingPwd.equals(passWord)){
                System.out.println("Thank you, credentials matched :");
            }else{
                System.out.println("The PASSWORD did not match :");
            }
        }else{ // If the username doesn't exist, then simply throw an error message

            System.out.println("The USER doesn't exist -");
        }

    }

    public static void main(String [] args){ // main method

        Login loginObj = new Login(); // Create an obj of class Login

        // As both the arrays are static, we can directly call without an object
        loginObj.loadCredentials(getUserNameArray(),getPasswordArray()); 
        
        // calling login method which has the logic to verify the credentials
        loginObj.login();

    } // end of main
} // end of program

Thank you,

All the best !!!