优化Java代码：使用除法和取模运算简化找零计算

public class ChangeCalculator {

    public static void rueckgaberechner(double geld) {
        System.out.println("Rueckgeld: ");

        // 将金额转换为分（整数）
        int geldInCent = (int) (geld * 100);

        // 计算2欧元硬币的数量
        int numberOf2Euros = geldInCent / 200;
        geldInCent %= 200;
        if (numberOf2Euros > 0) {
            System.out.println(numberOf2Euros + " mal 2 Euro");
        }

        // 计算1欧元硬币的数量
        int numberOf1Euros = geldInCent / 100;
        geldInCent %= 100;
        if (numberOf1Euros > 0) {
            System.out.println(numberOf1Euros + " mal 1 Euro");
        }

        // 计算50分硬币的数量
        int numberOf50Cents = geldInCent / 50;
        geldInCent %= 50;
        if (numberOf50Cents > 0) {
            System.out.println(numberOf50Cents + " mal 50 Cent");
        }

        // 计算20分硬币的数量
        int numberOf20Cents = geldInCent / 20;
        geldInCent %= 20;
        if (numberOf20Cents > 0) {
            System.out.println(numberOf20Cents + " mal 20 Cent");
        }

        // 计算10分硬币的数量
        int numberOf10Cents = geldInCent / 10;
        geldInCent %= 10;
        if (numberOf10Cents > 0) {
            System.out.println(numberOf10Cents + " mal 10 Cent");
        }

        // 计算5分硬币的数量
        int numberOf5Cents = geldInCent / 5;
        geldInCent %= 5;
        if (numberOf5Cents > 0) {
            System.out.println(numberOf5Cents + " mal 5 Cent");
        }

        // 计算2分硬币的数量
        int numberOf2Cents = geldInCent / 2;
        geldInCent %= 2;
        if (numberOf2Cents > 0) {
            System.out.println(numberOf2Cents + " mal 2 Cent");
        }

        // 计算1分硬币的数量
        int numberOf1Cents = geldInCent; // 剩余的都是1分
        if (numberOf1Cents > 0) {
            System.out.println(numberOf1Cents + " mal 1 Cent");
        }
    }

    public static void main(String[] args) {
        rueckgaberechner(3.88); // 测试用例
    }
}

import java.util.Arrays;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Function;
import java.util.stream.Collectors;

public class ChangeCalculator {

    enum EuroDenominations {
        ONE_CENT_COIN(1, "1¢"),
        TWO_CENT_COIN(2, "2¢"),
        FIVE_CENT_COIN(5, "5¢"),
        TEN_CENT_COIN(10, "10¢"),
        TWENTY_CENT_COIN(20, "20¢"),
        FIFTY_CENT_COIN(50, "50¢"),
        ONE_EURO_COIN(100, "€1"),
        TWO_EURO_COIN(200, "€2");

        private final int cents;
        private final String symbol;

        EuroDenominations(int cents, String symbol) {
            this.cents = cents;
            this.symbol = symbol;
        }

        public int cents() {
            return cents;
        }

        public String symbol() {
            return symbol;
        }
    }

    public static Map<EuroDenominations, Integer> rueckgaberechner(double geld) {
        AtomicReference<Double> atomicGeld = new AtomicReference<>(geld);
        return Arrays.stream(EuroDenominations.values())
                .sorted(Comparator.comparing(EuroDenominations::cents).reversed())
                .collect(Collectors.toMap(Function.identity(), v -> {
                            double g = atomicGeld.get();
                            int i = (int) (g / v.cents());
                            atomicGeld.set(g % v.cents());
                            return i;
                        },
                        (a, b) -> a,
                        LinkedHashMap::new));
    }

    public static void main(String[] args) {
        Map<EuroDenominations, Integer> rueckgaberechner = rueckgaberechner(3.88);
        System.out.println(rueckgaberechner);

        System.out.println("\nPretty print:");

        rueckgaberechner.entrySet().stream()
                .filter(entry -> entry.getValue() != 0)
                .forEach(entry -> System.out.printf("%d mal %s\n", entry.getValue(), entry.getKey().symbol()));
    }
}