Java遍历Map集合的三种方法

package com.xqnode;

import java.util.*;

/**
* 遍历map集合的三种方法
* Created by xiaqing on 2017/10/21.
*/
public class RunMain {
public static void main(String[] args){
System.out.println("Hello World!");
Map<String,Object> map = new HashMap <>();
map.put("a","a");
map.put("b",1);
map.put("c",false);
//方法一
Iterator <String> keyIterator = map.keySet().iterator();
while(keyIterator.hasNext()){
String key = keyIterator.next();
Object value = map.get(key);
System.out.println("key:"+key+",value:"+value);
}
//方法二
Iterator <Map.Entry <String, Object>> entryIterator = map.entrySet().iterator();
while (entryIterator.hasNext()){
Map.Entry <String, Object> mapEntry = entryIterator.next();
String key = mapEntry.getKey();
Object value = mapEntry.getValue();
System.out.println("key:"+key+",value:"+value);
}
//方法三
Collection <Object> values = map.values();
for (Object o: values) {
System.out.println(o);
}
}
}

map.forEach((k,v) -> System.out.println("key:"+k+",value:"+v));