Enumeration接口的一个实现

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

public class ListEnumeration<E> implements Enumeration<E> {
???
??? private List<E> list = new ArrayList<E>();
??? private int index = -1;
???
??? public ListEnumeration(){
??? ???
??? }
???
??? public void add(E e){
??? ??? list.add(e);
??? }

??? @Override
??? public boolean hasMoreElements() {
??? ??? if(list.isEmpty()){
??? ??? ??? return false;
??? ??? }
??? ???
??? ??? return index < (list.size() - 1);
??? }

??? @Override
??? public E nextElement() {
??? ??? index ++ ;
??? ??? return list.get(index);
??? }
???
}