时钟，泳池

 1 package com.fj;
 2 
 3 import java.util.Calendar;
 4 
 5 /**
 6  * 时钟类
 7  * @author 俊霖
 8  *
 9  */
10 public class Clock {
11     private int hour;
12     private int minute;
13     private int second;
14     
15     public Clock() {
16         Calendar calendar = Calendar.getInstance();
17         hour = calendar.get(Calendar.HOUR_OF_DAY);
18         minute = calendar.get(Calendar.MINUTE);
19         second = calendar.get(Calendar.SECOND);
20     }
21 
22     public void go() {
23         second++;
24         if (second >= 59) {
25             second = 0;
26             minute++;
27         }
28         if (minute >= 59) {
29             minute = 0;
30             hour++;
31         }
32         if (hour >= 23) {
33             hour = 0;
34         }
35     }
36     
37     public StringBuffer show() {
38         StringBuffer time = new StringBuffer();    
39         if (hour < 10) {
40             time.append("0");
41         }
42         time.append(hour + ":");
43         if (minute < 10) {
44             time.append("0");
45         }
46         time.append(minute + ":");
47         if (second < 10) {
48             time.append("0");
49         }
50         time.append(second);
51         return time;
52     }
53     
54     public int getHour() {
55         return hour;
56     }
57     public void setHour(int hour) {
58         this.hour = hour;
59     }
60     public int getMinute() {
61         return minute;
62     }
63     public void setMinute(int minute) {
64         this.minute = minute;
65     }
66     public int getSecond() {
67         return second;
68     }
69     public void setSecond(int second) {
70         this.second = second;
71     }
72     
73 }

 1 Clock clock = new Clock();
 2         for (int i = 0;i < 10; i++) {
 3             clock.go();
 4             System.out.println(clock.show());
 5             try {
 6                 Thread.sleep(1000);
 7             } catch (InterruptedException e) {
 8                 e.printStackTrace();
 9             }
10         }

 1 package com.fj;
 2 /**
 3  * 泳池
 4  * @author 俊霖
 5  *
 6  */
 7 public class Circle {
 8     private double radius;
 9     
10     public double getArea() {
11         double area = Math.PI * radius * radius;
12         return area;
13     }
14     
15     public double getCircumference() {
16         double circumference = 2 * Math.PI * radius;
17         return circumference;
18     }
19     
20     public double getRadius() {
21         return radius;
22     }
23 
24     public void setRadius(double radius) {
25         this.radius = radius;
26     }
27     
28     
29 }

1 Circle circle1 = new Circle();
2         Circle circle2 = new Circle();
3         double radius = Integer.parseInt(JOptionPane.showInputDialog("请输入泳池半径："));
4         circle1.setRadius(radius);
5         circle2.setRadius(radius + 3);
6         System.out.printf("装修过道需要%.2f元！\n",(circle2.getArea()-circle1.getArea()) * 10);
7         System.out.printf("修围墙需要%.2f元！",circle2.getCircumference() * 8);