[JAVA] 중복되지 않게 자료를 관리하는 Set 인터페이스를 구현한 클래스와 그 활용

HashSet 클래스

• Set 인터페이스를 구현한 클래스
• 멤버의 중복 여부를 체크하기 위해 인스턴스의 동일성을 확인해야 함
• 동일성 구현을 위해 필요에 따라 equals()와 hashCode() 메서드를 재정의함

 

Memeber.java

public class Member {
	
	
	private int memeberId;
	private String memberName;

	public Member(int memeberId, String memberName) {
		this.memeberId = memeberId;
		this.memberName = memberName;
	}

	public final int getMemeberId() {
		return memeberId;
	}

	public final void setMemeberId(int memeberId) {
		this.memeberId = memeberId;
	}

	public final String getMemberName() {
		return memberName;
	}

	public final void setMemberName(String memberName) {
		this.memberName = memberName;
	}

	@Override
	public String toString() {
		return memberName + " 회원님의 아이디는 " + memeberId + "입니다";
	}


	@Override
	public boolean equals(Object obj) {
		
		if(obj instanceof Member) {
			
			Member member = (Member)obj;
			
			if(this.memeberId == member.memeberId) {
				return true;
			}else {
				return false;
			}
			
		}
		return false;
		
	}
	
	
	@Override
	public int hashCode() {
		return memeberId;
	}
	

}

 

 

 

MemberHashSet.java

public class MemberHashSet {
	
	private HashSet<Member> hashset; // 제너릭으로 <> 안에 관리할 타입 작성 
	
	public MemberHashSet() {
		hashset = new HashSet<Member>(); // <> 다이아모든 연산자 안에 타입 생략 가능 
	}
	
	public MemberHashSet(int size) {
		hashset = new HashSet<Member>(size);
	}
	
	public void addMember(Member member) {
		hashset.add(member);
	}
	
	public boolean removeMember(int memberId) {
		
		Iterator<Member> ir = hashset.iterator();
		
		while(ir.hasNext()) {
			
			Member member = ir.next();
		
			int tempId = member.getMemeberId();
				if(tempId == memberId) {
					hashset.remove(member);
					return true;
				}
			}
		return false;
		
	}
	
	public void showAllMember() {
		
		for(Member member : hashset) {
			System.out.println(member);
		}
		System.out.println();
	}

}

MemberHashSetTest.java

public class MemberHashSetTest {

	public static void main(String[] args) {

		
		MemberHashSet memberHashSet= new MemberHashSet();
		
		Member memberLee = new Member(1001, "Lee");
		Member memberKim = new Member(1002, "Kim");
		Member memberKang = new Member(1003, "Kang");
		
		memberHashSet.addMember(memberLee);
		memberHashSet.addMember(memberKim);
		memberHashSet.addMember(memberKang);
		
		Member memberHong = new Member(1003, "Hong");
		memberHashSet.addMember(memberHong);
		
		memberHashSet.showAllMember();
		
		
		
		
	}

}