Java 15일차 2(Map Method)

 

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public class MapMethod {

	public static void main(String[] args) {
		
		Map<String, Object> map = new HashMap<String, Object>();
		
		map.put("username", "junil");
		map.put("password", "1234");
		map.put("name", "김준일");
		map.put("email", "junil@gamail.com");
		map.put("age", "29");
		map.put("gender", true);
		
		Map<String, String> address = new HashMap<>(); /*Hash 값에 따라서 순서대로 나온다. 완전 무작위 는 아니다.*/
		/* Map은 키와 밸류값.*/
		address.put("address1", "부산광역시");
		address.put("address2", "동래구");
		address.put("address3", "중앙대로 1285");
		
		map.put("address", address);
        
        Map<Integer, String> subject = new HashMap<>(); /*키값이 Integer 면 List와 같다.*/
		subject.put(100, "java");
		subject.put(200, "C#");
		subject.put(300, "python");
		subject.put(401, "python2");
		subject.put(403, "python3");
		subject.put(502, "python4");
		subject.put(604, "python5");
		
		map.put("subject", subject);
		
		System.out.println(map);
		
		Map<Integer, String> subject = new TreeMap<>(); /*트리맵 하면 순서대로*/
		subject.put(100, "java");
		subject.put(200, "C#");
		subject.put(300, "python");
		subject.put(401, "python2");
		subject.put(403, "python3");
		subject.put(502, "python4");
		subject.put(604, "python5");
		
		map.put("subject", subject); /*뒤의 subject 는 map , map object로 업캐스팅*/
		
		System.out.println(map);
        
        System.out.println(((Map<Integer,String>)map.get("subject")).get(403)); /*python3*/
		
		//System.out.println(((Map<Integer,String>)/*다운캐스팅*/map.get("subject")/*이건 Object*/).get(403)); /*python3*/
		
        List<String> hobby = new ArrayList<>();
		
		hobby.add("축구");
		hobby.add("농구");
		hobby.add("야구");
		hobby.add("족구");
		
		map.put("hobby", hobby);
		
		System.out.println(hobby);
		
		System.out.println(((List<String>)map.get("hobby")).get(2)); /*야구만 출력*/

	}

}

 

{password=1234, address={address3=중앙대로 1285, address2=동래구, address1=부산광역시}, gender=true, subject={100=java, 200=C#, 300=python, 401=python2, 403=python3, 502=python4, 604=python5}, name=김준일, email=junil@gamail.com, age=29, username=junil}
python3
[축구, 농구, 야구, 족구]
야구