import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

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 Main {
  public static void main(String[] args) {
    Set<String> set = new HashSet<String>();
    set.add("a");
    set.add("b");
    set.add("c");
    set.add("d");
    Enumeration<String> x = new IteratorEnumeration<String>(set.iterator());
    while (x.hasMoreElements()) {
      System.out.println(x.nextElement());
    }
  }
}

運行結果如下: