HashSet 실습

import java.util.HashSet;

import java.util.Iterator;

 

public class HashSetEx {

 

           /**

            * @param args

            */

           public static void main(String[] args) {

                     // TODO Auto-generated method stub

                     //ctrl + shift + O 단축키 = 자동으로 import

                     HashSet<String> set1 = new HashSet<String>();

                     HashSet set2 = new HashSet();

                    

                     set1.add("홍길동");

                     set1.add("박문수");

                     set1.add("이몽룡");

                               

                     System.out.println("크기 : " + set1.size());

                    

                     // 중복된 값은 제거됨.

                     set1.add("이몽룡");

                    

                     System.out.println("크기 : " + set1.size()); //크기가 똑같음

 

                     System.out.println(set1.toString());

                    

                     //사이즈가 없는 데이터의 출력

                     Iterator<String> i = set1.iterator();

                    

                     //hasNext() 다음 값이 있는지 물어봄, 없을때까지 루프

                     while(i.hasNext()){

                                System.out.println(i.next());

                     }

                    

                     // 제네릭이 안 정해져있으면 obj를 통해 형변환

                     for(Object obj : set1){

                                System.out.println((String)obj);

                     }

                    

                     //제네릭이 정해져있으면 String으로 받을 수 있음

                     for(String data : set1){

                                System.out.println(data);

                     }

           }

}

 

 

크기 : 3

크기 : 3

[박문수, 홍길동, 이몽룡]

박문수

홍길동

이몽룡

박문수

홍길동

이몽룡

박문수

홍길동

이몽룡