Тест: написать простейший финансовый калькулятор, работающий в консоли

public class Currency {
    public static void main(String[] args) {
 
 
        Scanner input = new Scanner(System.in);
        double value1 = 0.00, value2 = 0.00;
        String currency;
 
        System.out.print("Enter a value: ");
        String str = input.nextLine();
        value1 = Double.parseDouble(str);
        System.out.print("USD or EUR: ");
        currency = input.nextLine();
 
 
        if (currency.equals("USD")) {
            value2 = value1 * 0.734878047;
            System.out.println(value1 + "USD = " + value2 + " EUR. (Conversion rate: 1 USD = 0.734878047 EUR)");
        } else if (currency.equals("EUR")) {
            value2 = value1 * 1.36077;
            System.out.println(value1 + "EUR = " + value2 + " USD. (Conversion rate: 1 EUR = 1.36077 USD)");
        } else {
            System.out.println("Conversion rate: 1 USD = 0.734878047 EUR"
                    + "\nConversion rate: 1 EUR = 1.36077 USD");
        }
 
        input.close();
    }
}

  static Scanner key = new Scanner(System.in);
 
    public static void main(String[] args) {
 
        final double dollar = 12;
        final double euro = 52.5;
 
        int minus;
        int summa;
        double exchangeRate;
 
 
        System.out.println("Enter 0 to add a dollar + euro and convert to dollars or " + "1 to add euro + dollar and convert to euro:");
        summa = key.nextInt();
 
        //добавляем доллары к эвро и наоборот
 
        if (summa == 0) {
            System.out.println("How many dollars do you have");
            double Dollar = key.nextDouble();
            System.out.println("How many euro do you have");
            double Euro = key.nextDouble();
            exchangeRate = Dollar + ((euro / dollar) * Euro);
            System.out.println("$" + Dollar + " + " + Euro + "eur");
            System.out.println("You nave" + " $" + exchangeRate);
        } else if (summa == 1) {
            System.out.println("How many euro do you have");
            double Euro = key.nextDouble();
            System.out.println("How many dollars do you have");
            double Dollar = key.nextDouble();
            exchangeRate = Euro + ((dollar / euro) * Dollar);
            System.out.println(Euro + "eur " + "+" + " $" + Dollar);
            System.out.println("You have " + exchangeRate + "eur");
        }
        System.out.println("Enter 0 to add a dollar - euro and convert to dollars or " + "1 to add euro - dollar and convert to euro:");
        minus = key.nextInt();
 
 
        //Отнимаем долары от эвро и наоборот
        if (minus == 0) {
            System.out.println("How many dollars do you have");
            double Dollar = key.nextDouble();
            System.out.println("How many euro do you have");
            double Euro = key.nextDouble();
            exchangeRate = Dollar - ((euro / dollar) * Euro);
            System.out.println("$" + Dollar + " - " + Euro + "eur");
            System.out.println("You nave " + "$" + exchangeRate);
        } else if (minus == 1) {
            System.out.println("How many euro do you have");
            double Euro = key.nextDouble();
            System.out.println("How many dollars do you have");
            double Dollar = key.nextDouble();
            exchangeRate = Euro - ((dollar / euro) * Dollar);
            System.out.println(Euro + "eur " + "-" + " $" + Dollar);
            System.out.println("You have " + exchangeRate + "eur");
 
 
        }
        key.close();
    }

public class Money {
    private String name;
    private String sign;
    private double rateBuck; // курс этой валюты к баксу
    private double val;
 
    public Money(String name, String sign, double rateBuck) {
        this.name = name;
        this.sign = sign;
        this.rateBuck = rateBuck;
    }
 
    public double toThisValuta(Money otherValuta) {
        return otherValuta.getRateBuck() * otherValuta.getVal()/this.rateBuck;
    }
 
    public double getVal() {
        return val;
    }
 
    public void setVal(double val) {
        this.val = val;
    }
 
    public double getRateBuck() {
        return rateBuck;
    }
 
    public void setRateBuck(double rateBuck) {
        this.rateBuck = rateBuck;
    }
 
    public static void main(String[] args) {
        Money dollar = new Money("Dollar", "$", 1);
        Money ruble = new Money("Ruble", "R", 0.5);
        dollar.setVal(10);
        ruble.setVal(100);
        System.out.println(ruble.toThisValuta(dollar));
        System.out.println(dollar.toThisValuta(dollar));
        System.out.println(dollar.toThisValuta(ruble));
    }
}