[JAVA] Map - value로 key찾기

출처 : allg.tistory.com/18

[자료구조/Map] 자바 HashMap에서 value 값으로 key 값 찾기

 

 

import java.util.HashMap;
public class MapGetKeyFromeValue {

public static void main(String[] args) {

    HashMap<Integer, String> map = new HashMap<Integer, String>();

    map.put(1, "피카츄");
    map.put(2, "라이츄");
    map.put(3, "파이리");

    System.out.println("map.get(1) : " + map.get(1));
    System.out.println("map.get(2) : " + map.get(2));
    System.out.println("map.get(3) : " + map.get(3));
    System.out.println();

    //key값을 object 타입으로 반환
    System.out.println("getKeyFromValue(map, \"피카츄\") : " + getKey(map, "피카츄")); 
    System.out.println("getKeyFromValue(map, \"라이츄\") : " + getKey(map, "라이츄")); 
    System.out.println("getKeyFromValue(map, \"파이리\") : " + getKey(map, "파이리")); 
    System.out.println();

    //int형으로 변환 후 value 값 출력
    System.out.println(map.get( (int) getKey(map, "피카츄") ) );     
    System.out.println(map.get( (int) getKey(map, "라이츄") ) );     
    System.out.println(map.get( (int) getKey(map, "파이리") ) );     
}

public static Object getKey(HashMap<Integer, String> m, Object value) {

    for(Object o: m.keySet()) {

        if(m.get(o).equals(value)) {
            return o;
        }
    }
    return null;
}

}

 

 

출처: https://allg.tistory.com/18 [프로그래밍 해볼까]