Java: Enumeration from Set<String>

Question

I have a simple collections question. I have a Set<String> object. I want an Enumeration<String> of the Strings in that Set. I need an Enumeration<String> since I am overriding a method that specifically returns an Enumeration<String>. What is the cleanest/best way to go about it?

Answer 1

java.util.Collections.enumeration(set)

Javadoc

Returns an enumeration over the specified collection. This provides interoperability with legacy APIs that require an enumeration as input.

Answer 2

EDIT: There's no need to write your own (although I'll leave the implementation below for posterity) - see Kevin Bourrillion's answer for the one in the JDK.

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If you really need an enumeration, could could use:

Enumeration<String> x = new Vector(set).elements(); 

It would be better to use Iterable<E> if at all possible though...

A better alternative is to write a small wrapper class around Iterator<E>. That way you don't have to take a copy just to find an imlementation of Enumeration<E>:

import java.util.*;  class IteratorEnumeration<E> implements Enumeration<E> {     private final Iterator<E> iterator;      public IteratorEnumeration(Iterator<E> iterator)     {         this.iterator = iterator;     }      public E nextElement() {         return iterator.next();     }      public boolean hasMoreElements() {         return iterator.hasNext();     }  }   public class Test {     public static void main(String[] args) {         Set<String> set = new HashSet<String>();          Enumeration<String> x = new IteratorEnumeration<String>(set.iterator());     } }