JAVA大学实用教程实验指导4.2.1答案

P24      三角形,圆形和梯形的类封装       代码补完      

 

另:别人做2分钟就做完,而我要做2天还要去问别人,实在有够纱布的,快赶上FL那个纱布达人了,不过还算学到东西了,又向SCJP迈了一步了    :)

 

 

 

AreaAndLength.java

 

1. class Trangle
2. {
3.     double sideA,sideB,sideC,area,length;
4.     boolean boo;
5.     public Trangle(double a,double b,double c)
6.     {
7.         sideA=a;sideB=b;sideC=c;
8.         if(a+b>c&&b+c>a&&c+a>b)
9.         {
10.             boo=true;
11.         }
12.         else
13.             boo=false;
14.     }
15.     double getLength()
16.     {
17.         return sideA+sideB+sideC;
18.     }
19.     public double getArea()
20.     {
21.         if(boo)
22.         {
23.             double p=(sideA+sideB+sideC)/2.0;
24.             area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC));
25.             return area;
26.         }
27.         else
28.         {
29.             System.out.println("不是一个三角形,不能计算面积");
30.             return 0;
31.         }
32.     }
33.     public void setABC(double a,double b,double c)
34.     {
35.         sideA=a;sideB=b;sideC=c;
36.         if(a+b>c&&b+c>a&&c+a>b)
37.         {
38.             boo=true;
39.         }
40.         else
41.         {
42.             boo=false;
43.         }
44.     }
45. }
46. class Lader
47. {
48.     double above,bottom,height,area;
49.     Lader(double a,double b,double h)
50.     {
51.         above=a;bottom=b;height=h;
52.     }
53.     double getArea()
54.     {
55.         return (above+bottom)*height/2;
56.     }
57. }
58. class Circle
59. {
60.     double radius,area;
61.     Circle(double r)
62.     {
63.         radius=r;
64.     }
65.     double getArea()
66.     {
67.         return 3.14*radius*radius;
68.     }
69.     double getLength()
70.     {
71.         return 2*3.14*radius;
72.     }
73.     void setRadius(double newRadius)
74.     {
75.         radius=newRadius;
76.     }
77.     double getRadius()
78.     {
79.         return radius;
80.     }
81. }
83. public class AreaAndLength
84. {
85.     public static void main(String args[])
86.     {
87.         double length,area;
88.         Circle circle=null;
89.         Trangle trangle;
90.         Lader lader;
91.         Circle a=new Circle(1.0);
92.         Trangle b=new Trangle(3.0,4.0,5.0);
93.         Lader c=new Lader(3.0,5.0,2.0);
94.         length=a.getLength();
95.         System.out.println("圆的周长:"+length);
96.         area=a.getArea();
97.         System.out.println("圆的面积:"+area);
98.         length=b.getLength();
99.         System.out.println("三角形的周长:"+length);
100.         area=b.getArea();
101.         System.out.println("三角形的面积:"+area);
102.         area=c.getArea();
103.         System.out.println("梯形的面积:"+area);
104.         b.setABC(12, 34, 1);
105.         area=b.getArea();
106.         System.out.println("三角形的面积:"+area);
107.         length=b.getLength();
108.         System.out.println("三角形的周长:"+length);
109.     }
110. }