private void validateState() {
if (fAmount == null) {
throw new IllegalArgumentException("Amount cannot be null");
}
if (fCurrency == null) {
throw new IllegalArgumentException("Currency cannot be null");
}
if (fAmount.scale() > getNumDecimalsForCurrency()) {
throw new IllegalArgumentException(
"Number of decimals is "
+ fAmount.scale()
+ ", but currency only takes "
+ getNumDecimalsForCurrency()
+ " decimals.");
}
}
public int hashCode() {
if (fHashCode == 0) {
fHashCode = HASH_SEED;
fHashCode = HASH_FACTOR * fHashCode + fAmount.hashCode();
fHashCode = HASH_FACTOR * fHashCode + fCurrency.hashCode();
}
return fHashCode;
}
public Money minus(Money aThat) {
checkCurrenciesMatch(aThat);
return new Money(fAmount.subtract(aThat.fAmount), fCurrency);
}
public Money plus(Money aThat) {
checkCurrenciesMatch(aThat);
return new Money(fAmount.add(aThat.fAmount), fCurrency);
}
public String toString() {
return fAmount.toPlainString() + " " + fCurrency.getSymbol();
}
