1. 先第一种，为了解题而解题。
   
2. 
   
3. ==== Main.java ====
   
4. public class Main {
   
5. private double TotalHeight = 100;
   
6. private double CurHeight = 50;
   
7. 
   
8. public void drop(int times) {
   
9. if ((times - 1) == 0) {
   
10. return;
    
11. }
    
12. 
    
13. setTotalHeight(getTotalHeight() + 2 * getCurHeight());
    
14. setCurHeight(getCurHeight() / 2);
    
15. 
    
16. drop(times - 1);
    
17. }
    
18. 
    
19. public double getTotalHeight() {
    
20. return TotalHeight;
    
21. }
    
22. 
    
23. public void setTotalHeight(double totalHeight) {
    
24. TotalHeight = totalHeight;
    
25. }
    
26. 
    
27. public double getCurHeight() {
    
28. return CurHeight;
    
29. }
    
30. 
    
31. public void setCurHeight(double curHeight) {
    
32. CurHeight = curHeight;
    
33. }
    
34. 
    
35. public static void main(String[] args) {
    
36. Main main = new Main();
    
37. main.drop(2);
    
38. System.out.println("Total height is " + main.getTotalHeight());
    
39. System.out.println("Current height is " + main.getCurHeight());
    
40. }
    
41. }
    
42. 
    
43. ==== 然后是第二种 =====
    
44. 
    
45. ==== Main.java ====
    
46. package main;
    
47. 
    
48. import javax.swing.JFrame;
    
49. 
    
50. import panel.BallPanel;
    
51. import time.Delay;
    
52. 
    
53. public class MainFrame extends JFrame {
    
54. public MainFrame(String title) {
    
55. super(title);
    
56. }
    
57. 
    
58. public static void main(String[] args) {
    
59. Delay delay = new Delay();
    
60. 
    
61. MainFrame frame = new MainFrame("Hello JFrame");
    
62. BallPanel ballPanel = new BallPanel();
    
63. frame.add(ballPanel);
    
64. frame.setSize(500, 500);
    
65. frame.setVisible(true);
    
66. frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    
67. 
    
68. delay.initDelay();
    
69. 
    
70. ballPanel.setDelay(delay.getDelay());
    
71. ballPanel.loopDrop(0);
    
72. }
    
73. }

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1. 先第一种，为了解题而解题。
   
2. 
   
3. ==== Main.java ====
   
4. public class Main {
   
5. private double TotalHeight = 100;
   
6. private double CurHeight = 50;
   
7. 
   
8. public void drop(int times) {
   
9. if ((times - 1) == 0) {
   
10. return;
    
11. }
    
12. 
    
13. setTotalHeight(getTotalHeight() + 2 * getCurHeight());
    
14. setCurHeight(getCurHeight() / 2);
    
15. 
    
16. drop(times - 1);
    
17. }
    
18. 
    
19. public double getTotalHeight() {
    
20. return TotalHeight;
    
21. }
    
22. 
    
23. public void setTotalHeight(double totalHeight) {
    
24. TotalHeight = totalHeight;
    
25. }
    
26. 
    
27. public double getCurHeight() {
    
28. return CurHeight;
    
29. }
    
30. 
    
31. public void setCurHeight(double curHeight) {
    
32. CurHeight = curHeight;
    
33. }
    
34. 
    
35. public static void main(String[] args) {
    
36. Main main = new Main();
    
37. main.drop(2);
    
38. System.out.println("Total height is " + main.getTotalHeight());
    
39. System.out.println("Current height is " + main.getCurHeight());
    
40. }
    
41. }
    
42. 
    
43. ==== 然后是第二种 =====
    
44. 
    
45. ==== Main.java ====
    
46. package main;
    
47. 
    
48. import javax.swing.JFrame;
    
49. 
    
50. import panel.BallPanel;
    
51. import time.Delay;
    
52. 
    
53. public class MainFrame extends JFrame {
    
54. public MainFrame(String title) {
    
55. super(title);
    
56. }
    
57. 
    
58. public static void main(String[] args) {
    
59. Delay delay = new Delay();
    
60. 
    
61. MainFrame frame = new MainFrame("Hello JFrame");
    
62. BallPanel ballPanel = new BallPanel();
    
63. frame.add(ballPanel);
    
64. frame.setSize(500, 500);
    
65. frame.setVisible(true);
    
66. frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    
67. 
    
68. delay.initDelay();
    
69. 
    
70. ballPanel.setDelay(delay.getDelay());
    
71. ballPanel.loopDrop(0);
    
72. }
    
73. }

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