异常的抛出，捕获并处理

public class dong {

 public static void main(String[] args) {
  point p=new point(-1,3);
  point p1=new point(4,2);
  point p2=new point(3,3);
  rectangle r=new rectangle(p,2,6);
  triangle t=new triangle(p,p1,p2);

 }

}
class point {
public int x,y;
public point() {}
public point(int x,int y)throws IllegalArgumentException
{
this.x=x;
this.y=y;

if(x<0||y<0)
throw new IllegalArgumentException(x+y+"x或y是无效参数！");
}
}
class rectangle extends point{
public int width,length;
//public point point1(3,6);
public rectangle(point point1,int length,int width)throws IllegalArgumentException
{

this.length=length;
this.width=width;
if(length<0||width<0)
throw new IllegalArgumentException(length+width+"长或宽为无效参数！");
}
}
class triangle extends point{
public triangle(point point1,point point2,point point3)throws IllegalArgumentException
{
if(((point1.x-point2.y)-(point2.x-point1.y))+((point2.x-point3.y)-(point3.x-point2.y))+((point3.x-point1.y)-(point3.y-point1.x))==0)
throw new IllegalArgumentException("不能构成三角形，此为无效的参数！");
}
}

运行结果：

Exception in thread "main" java.lang.IllegalArgumentException: 2x或y是无效参数！
 at point.<init>(dong.java:23)
 at dong.main(dong.java:5)

实验心得：实验中共处理三个异常，如果给的条件不符合其取值范围，就会出现抛出异常，之后就会进行异常捕捉和处理。

异常处理方法为IllegalArgumentException()；