BANKINGSYSTEM,.java

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

class BankAccount {
    private String accountNumber;
    private double balance;

    public BankAccount(String accountNumber) {
        this.accountNumber = accountNumber;
        this.balance = 0.0;
    }

    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
            System.out.println("Deposited: $" + amount);
        } else {
            System.out.println("Invalid amount for deposit.");
        }
    }

    public void withdraw(double amount) {
        if (amount > 0 && balance >= amount) {
            balance -= amount;
            System.out.println("Withdrawn: $" + amount);
        } else {
            System.out.println("Invalid amount for withdrawal or insufficient balance.");
        }
    }

    public double getBalance() {
        return balance;
    }

    public String getAccountNumber() {
        return accountNumber;
    }
}

public class BankingSystem {
    private static Map<String, BankAccount> accounts = new HashMap<>();

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        while (true) {
            System.out.println("\nBanking System Menu:");
            System.out.println("1. Create Account");
            System.out.println("2. Deposit");
            System.out.println("3. Withdraw");
            System.out.println("4. Check Balance");
            System.out.println("5. Exit");
            System.out.print("Enter your choice: ");

            int choice = scanner.nextInt();
            scanner.nextLine();  // Consume the newline character

            switch (choice) {
                case 1:
                    createAccount(scanner);
                    break;
                case 2:
                    performTransaction(scanner, "deposit");
                    break;
                case 3:
                    performTransaction(scanner, "withdraw");
                    break;
                case 4:
                    checkBalance(scanner);
                    break;
                case 5:
                    System.out.println("Exiting the Banking System. Thank you!");
                    scanner.close();
                    return;
                default:
                    System.out.println("Invalid choice. Please choose a valid option.");
            }
        }
    }

    private static void createAccount(Scanner scanner) {
        System.out.print("Enter account number: ");
        String accountNumber = scanner.nextLine();

        if (accounts.containsKey(accountNumber)) {
            System.out.println("Account with the same account number already exists.");
        } else {
            BankAccount account = new BankAccount(accountNumber);
            accounts.put(accountNumber, account);
            System.out.println("Account created successfully.");
        }
    }

    private static void performTransaction(Scanner scanner, String transactionType) {
        System.out.print("Enter account number: ");
        String accountNumber = scanner.nextLine();

        if (accounts.containsKey(accountNumber)) {
            BankAccount account = accounts.get(accountNumber);

            if (transactionType.equals("deposit")) {
                System.out.print("Enter amount to deposit: $");
                double amount = scanner.nextDouble();
                account.deposit(amount);
            } else if (transactionType.equals("withdraw")) {
                System.out.print("Enter amount to withdraw: $");
                double amount = scanner.nextDouble();
                account.withdraw(amount);
            }
        } else {
            System.out.println("Account not found. Please check the account number.");
        }
    }

    private static void checkBalance(Scanner scanner) {
        System.out.print("Enter account number: ");
        String accountNumber = scanner.nextLine();

        if (accounts.containsKey(accountNumber)) {
            BankAccount account = accounts.get(accountNumber);
            System.out.println("Account Number: " + account.getAccountNumber());
            System.out.println("Balance: $" + account.getBalance());
        } else {
            System.out.println("Account not found. Please check the account number.");
        }
    }
}