使用迭代器遍历List、Set、Map

import java.util.*;

public class TestIterator {
    public static void main(String[] args) {
        testItetatorList();
        testItetatorSet();
        testItetatorMap();
    }
    public static void testItetatorList(){
        List<String> list =new ArrayList<>();
        list.add("aa");
        list.add("bb");
        list.add("cc");
//使用iterator遍历List
        for (Iterator<String> iter = list.iterator();iter.hasNext();){
            String temp =iter.next();
            System.out.println(temp);
        }
    }



    public static void testItetatorSet(){
        Set<String> set =new HashSet<>();
        set.add("aa");
        set.add("bb");
        set.add("cc");
//使用iterator遍历Set
        for (Iterator<String> iter = set.iterator();iter.hasNext();){
            String temp =iter.next();
            System.out.println(temp);
        }
    }



    public static void testItetatorMap(){
        Map<Integer,String> map1 =new HashMap<>();
        map1.put(100,"aa");
        map1.put(200,"bb");
        map1.put(300,"cc");

        //第一种遍历Map的方式
        Set<Map.Entry<Integer,String>> ss =map1.entrySet();
//使用iterator遍历Map
        for (Iterator<Map.Entry<Integer,String>> iter = ss.iterator(); iter.hasNext();){
            Map.Entry<Integer,String> temp =iter.next();
            System.out.println(temp.getKey()+"---"+temp.getValue());
        }


        //第二种遍历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));
        }
     }
}

aa
bb
cc
aa
bb
cc
100---aa
200---bb
300---cc
100---aa
200---bb
300---cc