Java: testing if an element belongs to a set

[Carlis]

I have an element E and want to know if it is equal to any object in the vector V.

Obviously I could make a loop and try each one after another, but is there any built in method that will do this for me? And, more important, would that save computing power?

 

[mundane]

Vector.contains(Object)

If you are using the Vector as a Set, you might want to reconsider and instead use one of the AbstractSet subclasses, instead of replicating the functionality yourself.

 

[Argo]

If you use HashSet then Set.contains() is returned in constant type (as opposed to O(n) on List implementations).

 

[IHateMyJob2004]

Anything that extends Set will do the trick. Like Argo said though, you need to understand data structures in order to get a fast implementation.

HashSet and TreeSet are usually fine. Worry about optimizing later once you know there is an issue. LinkedHashSet is a special structure that keeps the keys in the order that you inserted them into the Hashset.

Read this:
<a target=_blank class=ftalternatingbarlinklarge href="https://java.sun.com/j2se/1.5.0/docs/api/java/util/Set.html">https://java.sun.com/j2se/1......java/util/Set.html</a>
And pay attention to the "All Known Implementing Classes:" section.


Also, remember to implement Equals() and/or hashCode() in those objects that go in the Set.