Project: Console Bank Account

What you will build

A complete console bank account program the user can interact with. It shows a menu, lets them deposit, withdraw and check the balance, and keeps running until they choose to quit. You will use almost everything from this course in one project.

It pulls together: a class with encapsulation (Unit 3), a while loop and a switch menu (Unit 2), Scanner input (Unit 1), and try / catch for safety (Unit 4).

How the finished program flows

Before we write any code, here is the whole journey the running program takes, in order. Picture the user sitting at the terminal:

1. The program starts, creates one Account (balance 0) and a Scanner to read what the user types.
2. It shows the menu — options 1 to 4 — and asks the user to choose.
3. The user types a number and presses Enter; the program reads it with nextInt().
4. A switch sends that choice to the right action: 1 deposits, 2 withdraws, 3 shows the balance, 4 quits.
5. For 1 or 2, the program asks for an amount and calls deposit or withdraw, which check the amount first (no negatives, no overdrawing) before changing the balance.
6. If the user typed letters instead of a number, try / catch catches it, prints a friendly message, and the menu simply comes back.
7. After the action, the loop repeats from step 2 — the menu shows again — until the user chooses 4, which sets running to false and ends the program with "Goodbye!".

Notice this covers the everyday data actions: create/add money (deposit), read the balance (check balance), and update/reduce it (withdraw) — all guarded so the data stays valid. Now we build it in three small steps.

Step 1 — the Account class

First, a class that safely holds the balance. The field is private, and deposits and withdrawals go through checked methods.

public class Account {
    private double balance = 0;

    public double getBalance() {
        return balance;
    }

    public void deposit(double amount) {
        if (amount <= 0) {
            System.out.println("Deposit must be positive.");
            return;
        }
        balance = balance + amount;
        System.out.println("Deposited " + amount);
    }

    public void withdraw(double amount) {
        if (amount <= 0) {
            System.out.println("Withdrawal must be positive.");
        } else if (amount > balance) {
            System.out.println("Not enough money. Balance is " + balance);
        } else {
            balance = balance - amount;
            System.out.println("Withdrew " + amount);
        }
    }
}

Step 2 — the menu loop

Now the main program. It creates an Account, then loops forever showing a menu until the user picks 4 (Quit). A switch handles each choice.

import java.util.Scanner;

public class Bank {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        Account account = new Account();
        boolean running = true;

        while (running) {
            System.out.println();
            System.out.println("1) Deposit");
            System.out.println("2) Withdraw");
            System.out.println("3) Check balance");
            System.out.println("4) Quit");
            System.out.print("Choose an option: ");

            int choice = input.nextInt();

            switch (choice) {
                case 1:
                    System.out.print("Amount to deposit: ");
                    account.deposit(input.nextDouble());
                    break;
                case 2:
                    System.out.print("Amount to withdraw: ");
                    account.withdraw(input.nextDouble());
                    break;
                case 3:
                    System.out.println("Balance: " + account.getBalance());
                    break;
                case 4:
                    running = false;
                    System.out.println("Goodbye!");
                    break;
                default:
                    System.out.println("Please pick 1 to 4.");
            }
        }
    }
}

Step 3 — guard against bad input

If the user types letters instead of a number, nextInt() throws an exception and crashes. Wrap the choice in a try / catch so the program survives and asks again.

try {
    int choice = input.nextInt();
    // ... the switch goes here ...
} catch (Exception e) {
    System.out.println("That was not a number. Try again.");
    input.nextLine();   // clear the bad input
}

Your tasks

• Build the Account class with private balance and checked deposit / withdraw.
• Build the menu loop with a switch and the Quit option.
• Add try / catch so letters do not crash the program.
• Test it: deposit, withdraw too much (should be refused), check balance, then quit.

Stretch goals

• Add an account owner name field, set via the constructor, shown in the menu title.
• Keep a transaction count and show how many actions were done before quitting.
• Store several accounts in an ArrayList and let the user pick which one to use.