异常处理机制

class NoTriangleException extends Exception{

    NoTriangleException()
    {
        super();
    }

    NoTriangleException(String message)
    {
        super(message);
    }   
}

 class Triangle{
    int a,b,c;
    Triangle(int a,int b,int c) throws NoTriangleException
    {
        this.a = a;
        this.b = b;
        this.c = c;
        if(a<0||b<0||c<0)
        {
            throw new NoTriangleException("输入的三角形边长不能为负");
        }

        else if( a+b<=c||a+c<=b||b+c<=a ||a-b>=c||a-c>=b||b-c>=a)
        {
        throw new NoTriangleException("输入的三角形边长不合法");
        }
    }

    //求周长
    public int Get_C()
    {
        int C=0;
        C= a+b+c;
        return C;
    }

    //求面积
    public double Get_S()
    {
        double s = 0;
        double p =Get_C()/2;
        double t = p*(p-a)*(p-b)*(p-c);
        s = Math.sqrt(t);
        return s;
    }
}

public class Main {
    public static void main(String[] args) {
        try {
            Triangle ta1 = new Triangle(3, 4, 90);    
            System.out.println("周长为："+ta1.Get_C());
            System.out.println("面积为："+ta1.Get_S());     

        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }

        try {
            Triangle ta2 = new Triangle(3, -4, 5);   
            System.out.println("周长为："+ta2.Get_C());
            System.out.println("面积为："+ta2.Get_S());      

        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
           
        }

        try {
            Triangle ta3 = new Triangle(3, 4, 5);   
            System.out.println("周长为："+ta3.Get_C());
            System.out.println("面积为："+ta3.Get_S());   
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        
    }
    
}