Map的三種便利方式

package com.toltech.springboot;


import java.util.*;

/**
 * Created by Wgs on 2017/10/11
 * 遍歷集合
 */
public class Test {
    public static void main(String[] args) {
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("tom", 12);
        map.put("jack", 21);
        System.out.println("方式一");
        // 方式一
        Set set = map.entrySet();
        Iterator iterator = set.iterator();
        while (iterator.hasNext()) {
            Map.Entry me = (Map.Entry) iterator.next();
            Object key = me.getKey();
            Object value = me.getValue();
            System.out.println("key: " + key + "   value: " + value);
        }
        System.out.println("方式二");
        // 方式二
        for (String key : map.keySet()) {
            System.out.println("key: " + key + "   value: " + map.get(key));
        }
        System.out.println("方式三");
        // 方式三
        for (Map.Entry<String, Object> entry : map.entrySet()) {
            System.out.println("enty " + entry + "       key: " + entry.getKey() + "   value: " + entry.getValue());
        }

    }
}

方式一
key: tom   value: 12
key: jack   value: 21
方式二
key: tom   value: 12
key: jack   value: 21
方式三
enty tom=12       key: tom   value: 12
enty jack=21       key: jack   value: 21