遍历Map集合(4种方法)

package com.jeeplus.modules.util;

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

public class ErgodicMap {

    public static void main(String[] args) {

        Map<String,String> map = new HashMap<>();
        map.put("1","a");
        map.put("2","b");
        map.put("3","c");
        map.put("4","d");
        map.put("5","e");

        //第一种方法
        //普通遍历key、value
        for (String s : map.values()){
            System.out.println(s);
        }


        //第二种方法
        //通过map.entrySet中的iterator遍历key和value
        Iterator<Map.Entry<String, String>> iterator = map.entrySet().iterator();
        while (iterator.hasNext()){
            Map.Entry<String, String> entry = iterator.next();
            System.out.println(entry.getValue());
        //  System.out.println(entry.getKey());
        }

        //第三种方法(推荐)
        for (Map.Entry<String, String> entry : map.entrySet()) {
            System.out.println(entry.getValue());
        //  System.out.println(entry.getKey()+"===");
        }

        //第四种方法
        for (String s : map.keySet()) {
            System.out.println(map.get(s));
        }
    }
}