public class ThrowException
{   static double sqrt(double d) throws IllegalArgumentException
    {   if(d<0)
        {   IllegalArgumentException e=new IllegalArgumentException("不能對負數開平方");
            throw e;
        }
        return (Math.sqrt(d));
    }
    public static void main(String args[ ])
    {   System.out.println("IllegalArgumentException Demo");
        try
        {   System.out.println(sqrt(9));
            System.out.println(sqrt(-3));
        }
        catch(IllegalArgumentException e)
        {   System.out.println(e.getMessage( ));
        }
    }
}