shapesdemo.java

java入门经典教程 java入门经典教程 java入门经典教程

// 例2.7.3 ShapesDemo.java
interface Shape
{
	void draw();
}
class Circle implements Shape
{
	public void draw(){  System.out.println("Circle.draw()");}
}
class Square implements Shape
{
	public void draw() {  System.out.println("Square.draw()");}
}
class Triangle implements Shape
{
	public void draw() {  System.out.println("Triangle.draw()");}
}
public class ShapesDemo
{
	public static Shape randShape()
	{
		switch ( ( int )( Math.random() * 3 ) )
		{
			default:
			case 0: return new Circle();
			case 1: return new Square();
			case 2: return new Triangle();
		}
	}
	public static void main(String[] args)
	{
		Shape[] s = new Shape[5]; 
		for ( int i=0; i<s.length; ++i )
			s[i] = randShape();  // 随机生成5个图形类的对象
		for ( int i=0; i<s.length; ++i )
			s[i].draw();  // 晚绑定
	}
}