面向对象—梯形圆形

 1 double s;
        double x;
        double h;
        double getm()
        {
        return((s+x)*h/2);
        }
        //初始化上底、下底、高
        Ladder(double s1,double x1,double h1)
        {
           s=s1;
           x=x1;
           h=h1;
        }

 Ladder ladder=new Ladder(2,4,6);

 2 System.out.println("上底下底高分别是2,4,6的梯形的面积为："+ladder.getm()); 

double r;
    double getl()
    {
        return(2*3.14*r);
    }
    double getm()
    {
        return(3.14*r*r);
    }
    Circle (double r1)
    {
        r=r1;
    }

Circle circle=new Circle(3);
        System.out.println("半径是3的园的周长为："+circle.getl());
        System.out.println("半径是3的园的面积为："+circle.getm());
        

方法二：

double shangdi;
    double xiadi;
    double height;
    double mianji;   
    Ladder(double shangdi,double xiadi,double height)
    {
        //使用参数初始化属性
        //this  代表当前类
        this.shangdi=shangdi;
        this.xiadi=xiadi;
        this.height=height; 
    }
    //方法的命名，动词（第一个字母小写）+名称
    //void  便是无返回值，将void替换为返回值的类型double
    //返回值的类型，要写在方法的前面
    double getmianji()
    {
        //计算面积
        mianji=(this.shangdi+this.xiadi)*this.height/2;
        System.out.println("面积为："+this.mianji);
        //返回语句return
        return this.mianji;
    }
    //测试用main的方法
    public static void main(String[] args)
    {
        //构造梯形，
        Ladder ladder=new Ladder(2,4,6);
        double mj=ladder.getmianji();
        System.out.println("接收的返回值为："+mj);
        
    }

double r;
    double zhouchang;
    double mianji;
    Circle(double r)
    {
        this.r=r;
    }
    double getzhouchang()
    {
       zhouchang=2*3.14*this.r;
       System.out.println("半径是4的圆的周长为："+zhouchang);
       return zhouchang;
    }
    double getmianji()
    {
        mianji=3.14*this.r*this.r;
        System.out.println("半径是4的圆的面积为："+mianji);
        return mianji;
    }
    public static void main(String[] args)
    {
        Circle circle=new Circle(4);
        double zc=circle.getzhouchang();
        System.out.println("返回的周长为："+circle.getzhouchang());
        double mj=circle.getmianji();
        System.out.println("返回的面积为："+circle.getmianji());
    }