//6.6̬󶨾
//ShapeһͨýӿڣҲ˵УΣ״ɾ
class Shape
{
	void draw()
	{}
	void erase()
	{}
}
//าdrawΪÿ͵ļ״ṩ˶һ޶Ϊ
class Circle extends Shape
{
	void draw()
	{
		System.out.println("Բ");
	}
	void erase()
	{
		System.out.println("ȡԲ");
	}
}
class Square extends Shape
{
	void draw()
	{
		System.out.println("");
	}
	void erase()
	{
		System.out.println("ȡ");
	}
}
class Triangle extends Shape
{
	void draw()
	{
		System.out.println("");
	}
	void erase()
	{
		System.out.println("ȡ");
	}
}
//Զ̬
public class Binding_test
{
	public static void main(String args[])
	{
		Shape[] s = new Shape[9];
		int n;
		for(int i = 0;i<s.length;i++)
		{
			n=(int)(Math.random()*3);
			switch(n)
			{
				case 0: s[i] = new Circle();break;
				case 1: s[i] = new Square();break;
				case 2: s[i] = new Triangle();break;	
			}
		}
		for(int i = 0;i < s.length;i++)
		s[i].draw();
	}
}
