생성자, 다형성

생성자

class Date{
    private int year, month, day;
    String dayOfWeek;
    boolean holiday;
    
    public int getYear(){
        return this.year;
    }
    public int getMonth(){
        return this.month;
    }
    public int getDay(){
        return this.day;
    }
    
    public Date(int year, int month, int day){
        this.year=year;
        this.month = month;
        this.day = day;
    }
}

Date date = new Date(1993,10,05);
date.getDay();

 

다형성

interface BinaryOp{
    public int apply(int right, int left);
}
public class Adder implements BinaryOp{
    public int apply(int right, int left){
        return right+left;
    }
}

//다형성 구현
public class Multiplier implements BinaryOp{
    public int apply(int right, int left){
        return right*left;
    }
}

//오..!! 서브 타입이라서. 인터페이스가 객체로 형변환 되는거라서
void calc(BinaryOp binder, int i ,int j){
    System.out.println(binder.apply(i,j));
}


calc(new Adder(),1,2);
calc(new Multiplier(),1,2);