java集合

import java.util.*;

public class MapTest{
	
	public static void main(String[] args){
		
		Map persons = new HashMap();
		
		persons.put("10000","JACK");
		persons.put("10000","LISA");//key是唯一的
		persons.put("10011","EINSTEIN");
		persons.put("10087","JAME");
		persons.put("12984","MICHEAL");
		
		System.out.println(persons.size());//4
		
		System.out.println(persons.containsKey("10000"));//true,判断集合Key是否包含10000
		
		System.out.println(persons.containsValue("LISA"));//true,判断集合Value是否包含JAME
		
		System.out.println(persons.containsValue("LISA"));//true,判断集合Value是否包含JAME
		
		String k = "10000";
		Object v = persons.get(k);
		System.out.println(v);//JACK,通过key去获取value
		
		persons.remove("10087");
		System.out.println(persons.size());//3
		
		Collection values = persons.values();
		Iterator it = values.iterator();
		while(it.hasNext()){
			System.out.println(it.next());//JACK JACK MICHEAL,通过while循环去遍历集合
		}
		
		Set keys = persons.keySet();
		
		Iterator it2 = keys.iterator();
		
		while(it2.hasNext()){
			Object id = it2.next();
			Object name = persons.get(id);
			System.out.println(id+"-->"+name);//10000-->JACK 10011-->JACK 12984-->MICHEAL,遍历集合的key和value
		}
	}
}