HashCode wrong

[murkle]

The logic in HashCode is wrong - this will give the same answer if you send the numbers in a different order. hashcode += (value.hashCode() * 32);

http://stackoverflow.com/questions/892618/create-a-hashcode-of-two-numbers suggests hashcode += hashcode * 31 + value.hashCode();

[haumacher]

Why were the hashCode() implementations changed in comparison to the OpenJDK implementations anyway? GWT seems to support the required Double.doubleToLongBits(double) method, see http://www.gwtproject.org/doc/latest/RefJreEmulation.html

Good hashCode functions use prime numbers as multipliers - 32 is "not fully" prime. To build a hashCode from multiple numbers, there is no point in multiplying each number with the same prime before adding them. Instead, the current result must be multiplied with a prime before adding the next number.

Instead of

    public void append(Double value) {
        hashcode += (value.hashCode() * 32);
    }

something like that should be used:

    public void append(Double value) {
        hashcode = hashcode * 31 + value.hashCode();
    }

[murkle]

This project is from 7 years ago - I guess GWT didn't support hashCode() then :)