이것이 자바다 6장 확인문제

15번

public class MemberService {
	String id;
	String password;
	
	boolean login (String id, String password) {
		if(id=="hong" && password=="12345") {
			return true;
		}else {
			return false;
		}
	}
	void logout (String id) {
		System.out.println("로그아웃 되었습니다.");
	}
}

public class MemberServiceExample {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		MemberService memberService=new MemberService();
		
		boolean result =memberService.login("hong", "12345");
		if(result) {
			System.out.println("로그인 되었습니다.");
			memberService.logout("hong");
			
		}else {
			System.out.println("id 또는 password가 불일치 ");
			
		}
	}

}

16번

public class Printer {
	void println(int n) {
		System.out.println(n);
	}
	void println(boolean n) {
		System.out.println(n);
	}
	void println(double n) {
		System.out.println(n);
	}
	void println(String n) {
		System.out.println(n);
	}
}

 

public class PrinterExample {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Printer printer=new Printer();
		
		printer.println(10);
		printer.println(true);
		printer.println(5.7);
		printer.println("홍길동");

	}}

17번 

public class Printer {
	static void println(int n) {
		System.out.println(n);
	}
	static void println(boolean n) {
		System.out.println(n);
	}
	static void println(double n) {
		System.out.println(n);
	}
	static void println(String n) {
		System.out.println(n);
	}
}

public class PrinterExample {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Printer printer=new Printer();
		
		Printer.println(10);
		Printer.println(true);
		Printer.println(5.7);
		Printer.println("홍길동");

	}}

18번

public class ShopService {
	private static ShopService singleton=new ShopService();
	
	private ShopService() {
		
	}
	static ShopService getInstance() {
		return singleton;
	}
}

public class ShopServiceExample {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ShopService obj1=ShopService.getInstance();
		ShopService obj2=ShopService.getInstance();

		if(obj1==obj2) {
			System.out.println("ShopService 같은 객체입니다.");
		}else {
			System.out.println("ShopService 객체가 다르다 ");
		}
	}

}

19번

public class Account {
	int balance;
	static final int MIN_BALANCE=0;
	static final int MAX_BALANCE=1000000;
	
	public Account() {			}
	
	void setBalance(int balance) {
		if(balance>=0 && balance<=1000000)  {
			this.balance=balance;
		}
	}
	
	int getBalance() {
		return balance;
	}
}

public class AccountExample {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Account account=new Account();
		
		account.setBalance(10000);
		System.out.println("현재잔고"+account.getBalance());
		
		account.setBalance(-100);
		System.out.println("현재잔고 "+account.getBalance());
		
		account.setBalance(2000000);
		System.out.println("현재잔고"+account.getBalance());
		
		account.setBalance(300000);
		System.out.println("현재잔고"+account.getBalance());
	}

}

20번