19일

package Chapter08;

public abstract class Shape {
	int width = 3;
	int height = 4;
	int r = 5;
	abstract int area();
	abstract int circum();

}

class Cir extends Shape{
	
	public int area() {
		return (int) (3.14 * r * r);
	}
	
	public int circum() {
		return (int) (3.14 * r * 2);
	}
}

class Rect extends Shape{
	
	public int area() {
		return width * height;
	}	
	
	public int circum() {
		return (width + height)*2;
	}
}

class Tri extends Shape{
	public int area() {
		return width * height / 2;
	}
	
	public int circum() {
		return width + height + (int)Math.sqrt(width*width + height*height);
	}
}

class ShapeMain{
	public static void main(String[] args) {
		Rect rect = new Rect();
		Cir cir = new Cir();
		Tri tri = new Tri();
		System.out.println("사각형의 넓이" + rect.area());
		System.out.println("사각형의 둘레" + rect.circum());
		System.out.println("원의 넓이" + cir.area());
		System.out.println("원의 둘레" + cir.circum());
		System.out.println("삼각형의 넓이" + tri.area());
		System.out.println("삼각형의 둘레" + tri.circum());
}

시작합니다!

package Chapter08;

public abstract class Shape {

int width = 3;

int height = 4;

int r = 5;

abstract int area();

abstract int circum();

}

class Cir extends Shape{

 

public int area() {

return (int) (3.14 * r * r);

}

 

public int circum() {

return (int) (3.14 * r * 2);

}

}

class Rect extends Shape{

 

public int area() {

return width * height;

}

 

public int circum() {

return (width + height)*2;

}

}

class Tri extends Shape{

public int area() {

return width * height / 2;

}

 

public int circum() {

return width + height + (int)Math.sqrt(width*width + height*height);

}

}

class ShapeMain{

public static void main(String[] args) {

Rect rect = new Rect();

Cir cir = new Cir();

Tri tri = new Tri();

System.out.println("사각형의 넓이" + rect.area());

System.out.println("사각형의 둘레" + rect.circum());

System.out.println("원의 넓이" + cir.area());

System.out.println("원의 둘레" + cir.circum());

System.out.println("삼각형의 넓이" + tri.area());

System.out.println("삼각형의 둘레" + tri.circum());

}