面向对象—梯形圆形




 1 double s;
 2         double x;
 3         double h;
 4         double getm()
 5         {
 6         return((s+x)*h/2);
 7         }
 8         //初始化上底、下底、高
 9         Ladder(double s1,double x1,double h1)
10         {
11            s=s1;
12            x=x1;
13            h=h1;
14         }

1 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());

 1 double r;
 2     double getl()
 3     {
 4         return(2*3.14*r);
 5     }
 6     double getm()
 7     {
 8         return(3.14*r*r);
 9     }
10     Circle (double r1)
11     {
12         r=r1;
13     }

1 Circle circle=new Circle(3);
2         System.out.println("半径是3的园的周长为："+circle.getl());
3         System.out.println("半径是3的园的面积为："+circle.getm());
4

方法二：

 1 double shangdi;
 2     double xiadi;
 3     double height;
 4     double mianji;   
 5     Ladder(double shangdi,double xiadi,double height)
 6     {
 7         //使用参数初始化属性
 8         //this  代表当前类
 9         this.shangdi=shangdi;
10         this.xiadi=xiadi;
11         this.height=height; 
12     }
13     //方法的命名，动词（第一个字母小写）+名称
14     //void  便是无返回值，将void替换为返回值的类型double
15     //返回值的类型，要写在方法的前面
16     double getmianji()
17     {
18         //计算面积
19         mianji=(this.shangdi+this.xiadi)*this.height/2;
20         System.out.println("面积为："+this.mianji);
21         //返回语句return
22         return this.mianji;
23     }
24     //测试用main的方法
25     public static void main(String[] args)
26     {
27         //构造梯形，
28         Ladder ladder=new Ladder(2,4,6);
29         double mj=ladder.getmianji();
30         System.out.println("接收的返回值为："+mj);
31         
32     }

 1 double r;
 2     double zhouchang;
 3     double mianji;
 4     Circle(double r)
 5     {
 6         this.r=r;
 7     }
 8     double getzhouchang()
 9     {
10        zhouchang=2*3.14*this.r;
11        System.out.println("半径是4的圆的周长为："+zhouchang);
12        return zhouchang;
13     }
14     double getmianji()
15     {
16         mianji=3.14*this.r*this.r;
17         System.out.println("半径是4的圆的面积为："+mianji);
18         return mianji;
19     }
20     public static void main(String[] args)
21     {
22         Circle circle=new Circle(4);
23         double zc=circle.getzhouchang();
24         System.out.println("返回的周长为："+circle.getzhouchang());
25         double mj=circle.getmianji();
26         System.out.println("返回的面积为："+circle.getmianji());
27     }