private double shang;            private double xia;            private double gao;                                    public double Zhouchang(double a,double b, double c)            {                shang=a;                xia=b;                gao=c;                return a+b+c;            }Sanjiao sj=new Sanjiao();        System.out.println("三角形的周长为："+sj.Zhouchang(30.5,20,27.4));