using System;
public class DrawingObject
{
public virtual void Draw()
{
Console.WriteLine("I'm just a generic drawing object.");
}
}
说明
清单9-1 定义了DrawingObject类。这是个可以让其他对象继承的基类。该类有一个名为Draw()的方法。Draw()方法带有一个virtual修饰符,该修饰符表明:该基类的派生类可以重载该方法。DrawingObject类的 Draw()方法完成如下事情:输出语句"I'm just a generic drawing object."到控制台。
2.清单9-2. 带有重载方法的派生类:Line.cs, Circle.cs, and Square.cs
using System;
public class Line : DrawingObject
{
public override void Draw()
{
Console.WriteLine("I'm a Line.");
}
}
public class Circle : DrawingObject
{
public override void Draw()
{
Console.WriteLine("I'm a Circle.");
}
}
public class Square : DrawingObject
{
public override void Draw()
{
Console.WriteLine("I'm a Square.");
}
}
using System;
public class DrawDemo
{
public static int Main(string[] args)
{
DrawingObject[] dObj = new DrawingObject[4];
dObj[0] = new Line();
dObj[1] = new Circle();
dObj[2] = new Square();
dObj[3] = new DrawingObject();
foreach (DrawingObject drawObj in dObj)
{
drawObj.Draw();
}
return 0;
}
}