shape_ex.java

刘艺编著的java教程的课本习题加例题代码 很有用哦！

abstract class Shape    
{abstract protected double area();
 abstract protected void draw();}
class Rectangle extends Shape
{float width,length;
 Rectangle(float w,float l)
  {width=w;
   length=l;}
 public double area()
 { return width*length;}
  public void draw(){};
}
public class Shape_ex
{public static void main(String args[])
 {Rectangle rc=new Rectangle(6,12);
  System.out.println("The area of rectangle :  "+rc.area());}
}