Can someone re-write this Java 8 Stream?

IamtheWalrus · 29-03-2016 03:11PM #1

    public long getDiscountedPrice(Discount... discounts) {

        long discountSum = stream(discounts)
                .mapToLong(d -> d.discount(unmodifiableList(items)))
                .sum();
        return totalPrice - discountSum;
    }

public interface Discount {

    BigDecimal discount(List<String> items);
}

Currently, d.discount() returns a float. I want to change it to return BigDecimal because it's currency. Can someone help me rewritd this method? I'm new to Java 8.

IamtheWalrus · 29-03-2016 09:03PM

Or even in Java 6?

IamtheWalrus · 30-03-2016 02:09PM

Java 2?

Senna · 30-03-2016 10:03PM

I'm only learning java so my help is limited and you probably know a lot more that me, but....

Is this code working as a long (similar to float) at the moment? If it is then the discountSum variable is working as a long when it's taking in a BigDecimal, without the need to cast.

The return type of getDiscountPrice is a long.
In the method you have discountSum declared also as a long.
By changing both of those to BigDecimal would be a start, but as I'm unfamiliar with BigDecimal I'm not sure if it's that easy.

IamtheWalrus · 31-03-2016 10:08PM

private BigDecimal itemsDiscountFor(Discount[] discounts) {
        return stream(discounts)
                .map(d -> d.discount(unmodifiableList(items)))
                .reduce(ZERO, BigDecimal::add);
    }

Can someone re-write this Java 8 Stream?

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