HashMap / Set /Collection

HashMap / Set /Collection

import java.util.Collection;

import java.util.HashMap;

import java.util.Set;

public class MapTest {

public static void main(String[] args) {

// key/value , name/value 쌍으로 저장하는 방식

// key이용해서 value을 얻는다.

HashMap map = new HashMap();

map.put("name", "홍길동");

map.put("age", 20 );

map.put("height", 172.3F);

map.put("name", "이순신"); // 수정

System.out.println(map.get("name"));//이순신

System.out.println(map.get("age"));//20

System.out.println(map.get("height"));//172.3

//키값얻기

Set keys = map.keySet(); //[name, age, height]

System.out.println(keys);

// value값 얻기

Collection c = map.values();

System.out.println(c); //[이순신, 20, 172.3]

// 삭제

map.remove("age");

System.out.println(c); //[이순신, 172.3]

}//end main

}//end class