BankingApplication.java

import java.util.Scanner;

public class BankingApplication {

    static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {

        /*
        JAVA BANKING PROGRAM
        Helps understand the use of Methods. Beginner's project on a signature type of Java application.
        Basic characteristics and actions such as:
        create account, login and userbase system, check balance, add
        or remove balance, take a loan with time module, and more.
        INCLUDE Compound Interest Calculator here too.
        And a currency converter.
         */

        // DECLARE VARIABLES
        double balance = 0;
        boolean isRunning = true;
        int choice;

        // DISPLAY A MENU - user picks a choice, make deposit, show their balance, take a withdrawal etc.
        // Keep it displayed as long as isRunning Boolean is true, so invalid choices keep the program on.

        while(isRunning){
            System.out.println("***********");
            System.out.println("BANKING APP");
            System.out.println("***********");
            System.out.println("1) Show Balance");
            System.out.println("2) Make a Deposit");
            System.out.println("3) Withdraw Money");
            System.out.println("4) Exit");
            System.out.println("***********");


            // GET AND PROCESS USERS CHOICE
            System.out.print("Enter your choice (1-4): ");
            choice = scanner.nextInt();

            // An enhanced switch will be used to process the users' choice
            switch(choice){
                case 1 -> showBalance(balance);
                case 2 -> balance = balance + deposit();
                case 3 -> balance = balance - withdraw(balance);
                case 4 -> isRunning = false;
                default -> System.out.println(" - Invalid choice, please try again - ");
            }

        }

        // the exit message
        System.out.println("----------------");
        System.out.println("Thanks for using");
        System.out.println("----------------");

        // USING METHODS outside this main class
        // 1. showBalance()
        // 2. deposit()
        // 3. withdraw()
        // 4. EXIT MESSAGE
        //Later
        // 5. Compound Interest Calculator
        // 6. Currency Converter

        scanner.close();
    }

    static void showBalance(double balance){
        System.out.println("\nYour Balance");
        System.out.printf("£%.2f\n\n", balance);
    }

    static double deposit(){
        double amount;

        System.out.print("Enter an amount to deposit: ");
        amount = scanner.nextDouble();

        if(amount < 0){
            System.out.println("Amount cannot be negative");
            return 0;
        }
        else{
            return amount;
        }
    }

    static double withdraw(double balance){

        double amount;
        System.out.print("How much do you wish to withdraw from balance: ");
        amount = scanner.nextDouble();

        if(amount > balance){
            System.out.println("Insufficient funds to perform this withdrawal");
            return 0;
        }
        else if(amount < 0){
            //user inputs minus then amount, still process
            amount *= -1;
            return amount;
        }
        else{
            return amount;
        }
    }

}