Map集合的四种遍历方式

package com.mcy;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class Name {
    public static void main(String[] args) throws Exception {
        Map<String, String> map = new HashMap<>();
        map.put("name", "马春燕");
        map.put("age", "23岁啦");
        map.put("微信", "Mcy1032528317");
        map.put("QQ", "1032528317");
        map.put("爱好", "逛吃逛吃逛吃");

        //第一种:通过Map.keySet遍历key和value

        for (String key : map.keySet()) {
            System.out.println("key= " + key + " ;value= " + map.get(key));
        }

        System.out.println("------------------------------------------------ ");

        //第二种:通过Map.entrySet使用iterator遍历

        Iterator<Map.Entry<String, String>> iter = map.entrySet().iterator();
        while (iter.hasNext()) {
            Map.Entry<String, String> next = iter.next();
            System.out.println("key= " + next.getKey() + " ; value= " + next.getValue());
        }

        System.out.println("------------------------------------------------ ");

        //第三种:通过Map.entrySet遍历

        for (Map.Entry<String, String> entry : map.entrySet()) {
            System.out.println("key= " + entry.getKey() + " ; value= " + entry.getValue());
        }

        System.out.println("------------------------------------------------ ");

        //第四种:通过Map.values()遍历所有的value，但不能遍历key

        for (String str : map.values()) {
            System.out.println("value= " + str);
        }

    }

}

运行结果图片: