java Swing 按钮不显示、鼠标滑过才显示

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1. import javax.swing.*;
   
2. 
   
3. import java.awt.*;
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4. import java.awt.event.*;
   
5. import java.awt.image.ImageObserver;
   
6. 
   
7. public class Welcome extends JFrame{
   
8. /**
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9. *
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10. */
    
11. private static final long serialVersionUID = 1L;
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12. /**
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13. *
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14. */
    
15. private JButton JB,JB1,JB2,JB3;
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16. private JLabel JL;
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17. private Image img;
    
18. private Toolkit tool;
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19. 
    
20. Welcome(){
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21. super("欢迎来到科帮网");
    
22. setSize(600,500);
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23. setLocation(250, 150);
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24. Container container = getContentPane();
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25. tool = getToolkit();
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26. container.setLayout(null);
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27. 
    
28. JB = new JButton("查询学校景点信息");
    
29. JB1 = new JButton("查询2景点间的最短距离");
    
30. JB2 = new JButton("查询旅游路线");
    
31. JB3 = new JButton("退出");
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32. JL = new JLabel("欢迎使用校园导游咨询系统");
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33. img = tool.getImage("E://School.jpg");
    
34. 
    
35. JB.addActionListener(new MyMonitor());
    
36. JB1.addActionListener(new MyMonitor());
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37. JB2.addActionListener(new MyMonitor());
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38. JB3.addActionListener((new MyMonitor()));
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39. 
    
40. JL.setBounds(180, 20, 300, 40);
    
41. JB.setBounds(200, 60, 200, 30);
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42. JB1.setBounds(200, 100, 200, 30);
    
43. JB2.setBounds(200, 140,200, 30);
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44. JB3.setBounds(500, 400, 90, 30);
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45. 
    
46. 
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47. container.add(JB);
    
48. container.add(JB1);
    
49. container.add(JB2);
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50. container.add(JB3);
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51. container.add(JL);
    
52. 
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53. setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
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54. setVisible(true);
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55. 
    
56. }
    
57. 
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58. private class MyMonitor implements ActionListener{
    
59. 
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60. public void actionPerformed(ActionEvent e) {
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61. if(e.getSource()==JB){
    
62. new MyGraphy();
    
63. setVisible(false);
    
64. }
    
65. if(e.getSource()==JB1){
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66. new ShowLength();
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67. setVisible(false);
    
68. }
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69. if(e.getSource()==JB2){
    
70. new ShowView();
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71. setVisible(false);
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72. }
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73. 
    
74. if(e.getSource()==JB3){
    
75. System.exit(0);
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76. }
    
77. 
    
78. }
    
79. 
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80. }
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81. 
    
82. public void paint(Graphics g){
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83. g.drawImage(img, 100, 230, 400, 250, (ImageObserver) this);
    
84. 
    
85. }
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86. 
    
87. 
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88. public static void main(String[] args) {
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89. new Welcome();
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90. }
    
91. }
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复制代码

原因：paint方法被你重写了，但是你没处理好、所以要在 paint 方法前加super.paint(g)
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java宫城大师

  G( H+ q7 x5 `& }, g& C下来，学习一下。谢谢

woniu

这个项目太棒勒！下下来学习下！

wudizxt

不错不错不错不错

wudizxt

不错不错不错