iterator迭代器的使用_遍历List和Set和Map

版权声明： https://blog.csdn.net/weixin_40072979/article/details/82969801

迭代器为我们提供了统一的遍历容器的方式：

package com.jianshun;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

/**
 * 测试迭代器遍历 List,Set,Map
 * @author Administrator
 *
 */
public class TestIterator {
	public static void main(String[] args) {
		//testIteratorList();
		//testIteratorSet();
		testIteratorMap();
	}
	
    //遍历Map
	public static void testIteratorMap(){
		Map<Integer,String> map1 = new HashMap<Integer, String>();
		map1.put(100, "aa");
		map1.put(200, "bb");
		map1.put(300, "cc");
		
		//第一种遍历Map的方式
		Set<Entry<Integer,String>> ss = map1.entrySet();
		for(Iterator<Entry<Integer,String>> iter = ss.iterator(); iter.hasNext();){
			Entry<Integer,String> temp = iter.next();
			System.out.println(temp.getKey()+"--"+temp.getValue());
		}
		System.out.println("*********");
		//第二种Map的方式
		Set<Integer> keySet = map1.keySet();
		for(Iterator<Integer> iter = keySet.iterator(); iter.hasNext();){
			Integer key = iter.next();
			System.out.println(key+"--"+map1.get(key));
		}
	}
	
    //遍历Set
	public static void testIteratorSet(){
		Set<String> set = new HashSet<String>();
		set.add("aa");
		set.add("bb");
		set.add("cc");
		
		//使用迭代器遍历set
		for(Iterator<String> iter = set.iterator(); iter.hasNext();){
			String temp = iter.next();
			System.out.println(temp);
		}
	}
	
    //遍历List
	public static void testIteratorList(){
		List<String> list = new ArrayList<String>();
		list.add("aa");
		list.add("bb");
		list.add("cc");
		
		//使用迭代器遍历List
		for(Iterator<String> iter = list.iterator(); iter.hasNext();){
			String temp = iter.next();
			System.out.println(temp);
		}
	}
}