Question

You are to write a Java program using the following instructions to build a bank-ATM server system with sockets.

A bank holds accounts that can have deposits, withdrawals, or retrievals of balance. The bank server provides the account for transactions when a client uses and ATM machine. The ATM asks for the type of transaction and the amount (if needed), then creates a socket connection to the bank to send the transaction for processing. The bank performs the transaction on the account and returns the balance to the client at the ATM. The following are some vague descriptions of the various packages, classes, etc., that the program must have. You will have to make your own decisions on how to approach it.

Server

• Bank package
  • Account class
    • Private variable balance
    • Constructor to set the initial balance
    • Deposit method to add an amount and return the new balance
    • Withdraw method to subtract and amount and return the new balance
    • Balance method to return the balance
  • Banker class
    • Main method
    • Instantiates an account to be used by the server
    • Instantiates an account server using a port number and the account
    • Starts the server
  • Account Server class
    • Private variables for sockets and object streams
    • Private variable for the account
    • Constructor to instantiate the server socket on the port and set the account
    • Server method
      • Outputs “Waiting for connection…”
      • Continuously loops
        • Accept a client
        • Receives a transaction object from the client
        • Determine the type of transaction and performs it
        • Sends “Transaction Complete: Balance is $” to the client
• Transaction package
  • Transaction class
    • Private variables of transaction type and amount
      • Transaction type can be a deposit, withdrawal, retrieve balance
    • Constructor to set the type and amount
    • Method to get the transaction type
    • Method to get the transaction amount

Client

• ATM class
  • Main method
  • Instantiates the client using an ip and port
  • Starts the client (the transaction method)
• Client class
  • Private variables for socket and object streams
  • Constructor to instantiate the client socket
  • Transaction method
    • Prompt the user for the type: “Type (1-deposit, 2-withdraw, 3-balance)?”
    • Prompt the user for the amount unless type 3, which should set amount to zero
    • Instantiate a Transaction object
    • Send the Transaction object to the server
    • Receive and display the response from the server
• Transaction package (must be the same as in Lab 10 Server)
  • Transaction class (must be the same as in Lab 10 Server)
    • Private variables of transaction type and amount
      • Transaction type can be a deposit, withdrawal, retrieve balance
    • Constructor to set the type and amount
    • Method to get the transaction type
    • Method to get the transaction amount

You can see an example of expected output here:

https://web.microsoftstream.com/video/662fcb3d-cf43-4164-a74b-6187dfc8aff6

Answer 1

Made a simple java program for ATM server:
import java.util.*;
public class ATM {

    public static Scanner kbd = new Scanner(System.in);
    // The checkID method determines if acctNum is a valid account number
    // and pwd is the correct password for the account.  If the account information
    // is valid, the method returns the current account balance, as a string.
    // If the account information is invalid, the method returns the string "error".
    public static String checkID(String acctNum, String pwd)
    {
        String result = "error";

        // Strings a, b, and c contain the valid account numbers and passwords.
        // For each string, the account number is listed first, followed by
        // a space, followed by the password for the account, followed by a space,
        // followed by the current balance.
        String a = "44567-5 mypassword 520.36";
        String b = "1234567-6 anotherpassword 48.20";
        String c = "4321-0 betterpassword 96.74";

        if (acctNum.equals(a.substring(0, a.indexOf(" "))) && 
                pwd.equals(a.substring(a.indexOf(" ")+1,a.lastIndexOf(" "))))
            return result = a.substring(a.lastIndexOf(" ") + 1);

        if (acctNum.equals(b.substring(0, b.indexOf(" "))) && 
                pwd.equals(b.substring(b.indexOf(" ")+1,b.lastIndexOf(" "))))
            return result = b.substring(b.lastIndexOf(" ") + 1);

        if (acctNum.equals(c.substring(0, c.indexOf(" "))) && 
                pwd.equals(c.substring(c.indexOf(" ") + 1,c.lastIndexOf(" "))))
            return result = c.substring(c.lastIndexOf(" ") + 1);

        return result;
    }

    public static int menu()
    {
        int menuChoice;
        do
        { 
            System.out.print("\nPlease Choose From the Following Options:"
                    + "\n 1. Display Balance \n 2. Deposit"
                    + "\n 3. Withdraw\n 4. Log Out\n\n");

            menuChoice = kbd.nextInt();

            if (menuChoice < 1 || menuChoice > 4){
                System.out.println("error");
            }

        }while (menuChoice < 1 || menuChoice > 4);

        return menuChoice;
    }

    public static void displayBalance(double x)
    {
        System.out.printf("\nYour Current Balance is $%.2f\n", x);
    }

    public static double deposit(double x, double y)
    {
        double depositAmt = y, currentBal = x;
        double newBalance = depositAmt + currentBal;

        System.out.printf("Your New Balance is $%.2f\n",  newBalance);

        return newBalance;
    }

    public static double withdraw(double x, double y)
    {
        double withdrawAmt = y, currentBal = x, newBalance;

        newBalance = currentBal - withdrawAmt;
        System.out.printf("Your New Balance is %.2f\n",newBalance);

        return newBalance;  
    }

    public static void main(String[] args) {

        String accNum, pass, origBal = "error";
        int count = 0, menuOption = 0;
        double depositAmt = 0, withdrawAmt = 0, currentBal=0; 
        boolean  foundNonDigit;
        //loop that will count the number of login attempts
        //you make and will exit program if it is more than 3.
        //as long as oriBal equals an error.  
        do{
            foundNonDigit = false;
            System.out.println("Please Enter Your Account Number: ");
            accNum = kbd.next();

            System.out.println("Enter Your Password: ");
            pass = kbd.next();

            origBal = checkID(accNum, pass);

            count++;

            if (count >= 3 && origBal.equals("error")){
                System.out.print("Maximum Login Attempts Reached.");
                System.exit(0);
            }
            if (!(origBal.equals("error"))){
                System.out.println("\nYour New Balance is: $ "+ origBal);
            }
            else
                System.out.println(origBal);


        }while(origBal.equals("error"));

        currentBal=Double.parseDouble(origBal);
        //this loop will keep track of the options that 
        //the user inputs in for the menu. and will 
        //give the option of deposit, withdraw, or logout.

        while (menuOption != 4)
        { 
            menuOption=menu();
            switch (menuOption)
            {
            case 1:
                displayBalance(currentBal);
                break;
            case 2:
                System.out.print("\nEnter Amount You Wish to Deposit: $ ");
                depositAmt = kbd.nextDouble();
                currentBal=deposit(depositAmt, currentBal);
                break;
            case 3:
                System.out.print("\nEnter Amount You Wish to Withdrawl: $ ");
                withdrawAmt = kbd.nextDouble();

                while(withdrawAmt>currentBal){
                    System.out.print("ERROR: INSUFFICIENT FUNDS!! "
                            + "PLEASE ENTER A DIFFERENT AMOUNT: $");
                    withdrawAmt = kbd.nextDouble();
                }

                currentBal = withdraw(currentBal, withdrawAmt);
                break;
            case 4:
                System.out.print("\nThank For Using My ATM.  Have a Nice Day.  Good-Bye!");
                System.exit(0);
                break;
            }
        }
    }
}