自定义迭代器

   自定义迭代器，它用于过滤超过一定长度的字符串的迭代器：

import java.util.Iterator;
import java.util.NoSuchElementException;

public class ShortStringItertor implements Iterator {
	private Iterator strings; //需要迭代的字符串迭代器
	private String nextShort; //如果没有下一个则为null
	private final int maxLen;//需要迭代的长度
	public ShortStringItertor(int maxLen, Iterator strings) {
		this.maxLen = maxLen;
		this.strings = strings;
		this.nextShort = null;
	}
	public boolean hasNext() {
		if(nextShort!=null) return true;
		while(strings.hasNext()){
			nextShort = (String)strings.next();
			if(nextShort.length()<=maxLen) return true;
		}
		nextShort = null;
		return false;
	}
	public Object next() {
		if(nextShort==null&&!hasNext()) throw new NoSuchElementException();
		String n = nextShort;
		nextShort = null;
		return n;
	}
	public void remove() {
	}

}

 

迭代器的使用：

public static void main(String[] args) {
		List<String> list = new ArrayList<String>();
		list.add("asdfsafasfd");
		list.add("asdsfd");
		list.add("asdfsafad");
		list.add("asdfsfd");
		list.add("afsafasfhgddfghdg");
		list.add("asdfsfd");
		list.add("aafasdgfdfgdfgfd");
		list.add("asfasfd");
		list.add("asfd");
		list.add("asdasfd");
		Iterator<String> it = new ShortStringItertor(10,list.iterator());
		while(it.hasNext()){
			System.out.println(it.next());
		}
	}