编写程序TestAbstract--电科大中山--P73第7题

编写程序TestAbstract–电科大中山–P73第7题

abstract class Shape{
	public double area;
	abstract double getArea();
}
class Rectangle extends Shape{
	public double length;
	public double width;
	public Rectangle(double length, double width) {
		super();
		this.length = length;
		this.width = width;
	}
	public double getArea() {
		return length*width;
	}
	
}
class Circle extends Shape{
	public double radius;
	public Circle(double radius) {
		super();
		this.radius = radius;
	}
	public double getArea() {
		return radius*radius*Math.PI;
	}
	
}
public class TestAbstract {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Rectangle s1 = new Rectangle(4,5);
		System.out.println(s1.getArea());
		Shape s2 = new Circle(3);
		System.out.println(s2.getArea());
	}

}