다형성 활용의 예제 - 2022-09-26

//1. 다형성이 적용되면 부모 = 자식

//2. 다형성에서 오버라이딩은 자식의 것.

class Shape {
	public Shape() {
		System.out.println("도형입니다.");
	}

	public void draw() {
		System.out.println("도형을 그립니다.");
	}
	
	public double getArea() {
		return 0.0;
	}
	
}

class Rectangle extends Shape {
	
	private double width,height;
	
	
	public Rectangle() {
		System.out.println("사각형 생성자");
	}

	public Rectangle(double width, double height) {
		this.width = width;
		this.height = height;
	}

	@Override
	public void draw() {
		System.out.println("사각형 도형을 그립니다.");
	}
	
	@Override
	public double getArea() {
		return width * height;
	}
}

class Triangle extends Shape {
	
	private double width,height;
		
	public Triangle() {
		System.out.println("삼각형 생성자");
	}
	
	public Triangle(double width, double height) {
		this.width = width;
		this.height = height;		
	}

	@Override
	public void draw() {
		System.out.println("삼각형 도형을 그립니다.");
	}
	
	@Override
	public double getArea() {
		return width * height / 2.0;
	}

}


public class Poly {
	public static void main(String[] args) {

		Shape[] shape = {new Triangle(10,10),new Rectangle(10,10)};
		
		double sumArea = 0;
		
		for (Shape s : shape) {
			sumArea += s.getArea();			
		}
		
		System.out.println(sumArea);
		
	}
}