java map的遍历

闲来无事，学习java基础–Map

package com.crazzy.day01;import java.util.HashMap;import java.util.Iterator;import java.util.Map;/** * Created by qqg on 2017/9/20. */public class MapDemo {    public static void main(String[] args) {        Map<String,String> map = new HashMap<>();        map.put("2","1995");        map.put("3","2005");        map.put("1","1985");        System.out.println("第一种遍历(普遍)：");        for(String key : map.keySet()){            System.out.println("key -> " + key + ": value -> " + map.get(key));        }        System.out.println("第二种遍历（迭代器）：");        Iterator<Map.Entry<String,String>> it = map.entrySet().iterator();        while (it.hasNext()){            Map.Entry<String,String> entry = it.next();            System.out.println("key ->" + entry.getKey() + ": value ->" + entry.getValue());        }        System.out.println("第三种方法（大容量）:");        for (Map.Entry<String,String> entry : map.entrySet()){            System.out.println("key ->" + entry.getKey() + ": value ->" + entry.getValue());        }    }}

运行结果：

可以看出，map会按照key的值自动进行排序。