package chapter14;
import java.util.*;
abstract class Shape{
	void draw(){
		System.out.println(this+".draw()");
	}
	
	abstract public String toString();
}

class Circle extends Shape{
	public String toString(){
		return "Circle";
	}
}

class Square extends Shape{
	public String toString(){
		return "Square";
	}
}

class Triangle extends Shape{
	public String toString(){
		return "Triangle";
	}
}

public class Shapes {
	public static void main(String args[]){
		List<Shape> shapeList=Arrays.asList(new Circle(),new Square(),new Triangle());
		for(Shape shape:shapeList){
			shape.draw();
		}
	}
	/*
	 * 繼承了類Shape，每個派生類都會覆蓋toString（）方法，this接受返回的String.
	 */

}