实验九.接口

一.源程序
package error;

public class Throwerror {

     public static void main(String[] args) throws IllegalArgumentException
     {    Point point1=new Point (3,1);
          Point point2=new Point (6,2);
          Point point3=new Point (9,3);
          new Rectangle(point1, -12,3);
           new Triangle(point1,point2,point3);
         Point[] point= {point1,point2};
         new Polygon(point);
         }
 
     }
    
     class Point
     {   public Point() {};
         public int x;
         public int y;
         public Point(int x,int y)
        {   this.x=x;
            this.y=y;
            
             if(x<0||y<0)
                 throw new IllegalArgumentException("Point中无效参数异常");
            }
         }
     class Rectangle extends Point
     {
         public int length,width;
     public Rectangle(Point point1,int length,int width) {
             this.length=length;
            this.width=width;
             if(length<0||width<0)
                throw new IllegalArgumentException("Rectangle无效参数异常");
        }
         }
     class Triangle extends Point 
     {
        
         public Triangle(Point point1,Point point2,Point point3) {
             if(point1.x/point1.y==point2.x/point2.y&&point2.x/point2.y==point3.x/point3.y)
                 throw new IllegalArgumentException("Triangle无效参数异常");
             }
         }
    
     class Polygon extends Point
     {   int i=0;
         public Polygon(Point[] points)
         { i=points.length;
       if(i<=2)
             throw new IllegalArgumentException("Polygon无效参数异常");
             }
     
     }