Re: Newbie question: How to write a set?

mrstephengross wrote:

    
class Foo {
        public boolean equals(Object obj) {
            // return true iff obj is a Foo
            // that you consider "equal" to this one
        }

        public int hashCode() {
            // return an integer whose value depends
            // only on those aspects of a Foo that
            // equals() takes into consideration
        }
    }

The important thing is to implement *both* equals() and
hashCode(), or to implement *neither* of them. It is
almost always a misteak to implement just one of the pair.

    
Set<Foo> set = new HashSet<Foo>();
    // or LinkedHashSet<Foo>();
    // or TreeSet<Foo>();
    // or ...

The type of the `set' reference should usually be Set,
sometimes SortedSet, but very rarely HashSet or TreeSet
or whatever.

--
Eric.Sosman@sun.com