HashMap遍历之EntrySet

遍历之EntrySet"/>

HashMap遍历之EntrySet

entry可以获取key和value的具体值

当entry<key,value> 

 public static void main(String[] args) {Map map = new HashMap();map.put("邓超", "孙俪");//替换map.put("王宝强", "马蓉");//okmap.put(null, "刘亦菲");//plmap.put("鹿晗", null);//okmap.put("lu汉", "刘亦菲");map.put("沫年", "刘亦菲");//okSystem.out.println(map);System.out.println("\n==========迭代器===========\n");Iterator ito3 = entrySet.iterator();while(ito3.hasNext()){Map.Entry entry2 = (Map.Entry) ito3.next();System.out.println(entry2.getValue());}//        Iterator ito3 = entrySet.iterator();
//        while(ito3.hasNext()){
//          Object entry = ito3.next();System.out.println(entry);//HashMap$Node ---实现 > Map.Entry (getKey,getValue)
//          //向下转型 Map.Entry
//          Map.Entry m = (Map.Entry) entry;
//            System.out.print(m.getValue()+" ");
//        }}

当entry<key,Object>,此时value = Object  

    public static void main(String[] args) {/*** 使用HashMapp添加三个员工对象，要求* 键：员工id* 值：员工对象** 并且遍历显示工资>18000的员工(遍历方式最少两种)* 员工类：姓名、工资、员工id*/Map map = new HashMap();map.put(1, new Employee("smith", 18000, "20001206"));map.put(2, new Employee("tom", 28000, "20011212"));map.put(3, new Employee("smith", 10000, "20111010"));System.out.println("员工的个数为：" + map.size());System.out.println("=========第三种遍历方式=========");Set set = map.entrySet();//先将map转化为entrySetIterator ito2 = set.iterator();//构建迭代器while (ito2.hasNext()){//迭代器循环条件Map.Entry entry = (Map.Entry) ito2.next();//将entrySet 转化为entry,并且向下移动指针//通过entry来获取key和valueEmployee emp = (Employee) entry.getValue();//将包entry向下转型为EmployeeSystem.out.println(emp);}
}