我的自定義類是和類Money的一種包裝。BigDecimalorg.joda.money.Money與之前一樣BigDecimal，我需要Money.ZERO在我的應用程序中使用 a （通常在reduce()操作中）。我發(fā)現(xiàn)我Money.ZERO在應用程序執(zhí)行期間的更改（它的amount值可能非零）導致無效結果。下面是我的自定義Money類：@Getter@Embeddable@NoArgsConstructor(access = AccessLevel.PRIVATE)@AllArgsConstructor(access = AccessLevel.PRIVATE)public class Money implements Serializable {    private static final long serialVersionUID = -4274180309004444639L;    public static final Money ZERO = new Money(BigDecimal.ZERO, CurrencyUnit.EUR);    private BigDecimal amount;    @Convert(converter = CurrencyUnitToStringConverter.class)    private CurrencyUnit currency;    public static Money of(BigDecimal amount, CurrencyUnit currency) {        return new Money(amount, currency);    }    public Money add(Money addition) {        checkCurrency(addition);        amount = amount.add(addition.getAmount());        return new Money(amount, currency);    }    public Money substract(Money reduction) {        checkCurrency(reduction);        amount = amount.subtract(reduction.getAmount());        return new Money(amount, currency);    }    private void checkCurrency(Money other) {        if (!Objects.equal(getCurrency(), other.getCurrency())) {            throw new IllegalArgumentException("Currency does not match when adding amounts!");        }    }所以我的目標是擁有一個ZERO數(shù)量BigDecimal.ZERO永遠保持不變的領域。