在Java中，NetBeans的動態創建dcheckbox

Question

我開發一個簡單的「任務列表」的應用程序，包括獲得「事做」的 某一天從數據庫和麪板擱在一個上顯示它們的複選框文本frame.There是一個按鈕「完成」，可用於去除 的勾選複選框後任務完成。

我用於動態創建的複選框的代碼如下所示：

//cnt-variable used to store the number of tasks for a day  
//rs1-ResultSet variable into which the task description is read into.  
//DATA-variable with 'to-do' description 

for(int i=0;i<cnt&&rs1.next();i++) 
{ 
    String s2=rs1.getString("DATA"); 
    JCheckBox cb = new JCheckBox("New CheckBox"); 
    cb.setText(s2); 
    cb.setVisible(true); 

    jPanel1.add(cb); 
    jPanel1.validate(); 
} 

在運行代碼中的所有它顯示是與面板的空幀。可能有人幫助我弄清楚爲什麼沒有被顯示的複選框？ 在此先感謝。

Answer 1

試試這個。這允許您創建的複選框的隨機數...

public class TestCheckboxes { 

    public static void main(String[] args) { 
     new TestCheckboxes(); 
    } 

    public TestCheckboxes() { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
       } catch (ClassNotFoundException ex) { 
       } catch (InstantiationException ex) { 
       } catch (IllegalAccessException ex) { 
       } catch (UnsupportedLookAndFeelException ex) { 
       } 

       JFrame frame = new JFrame(); 
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
       frame.setLayout(new BorderLayout()); 
       frame.add(new CheckBoxPane()); 
       frame.setSize(400, 400); 
       frame.setLocationRelativeTo(null); 
       frame.setVisible(true); 
      } 

     }); 
    } 

    public class CheckBoxPane extends JPanel { 

     private JPanel content; 

     public CheckBoxPane() { 
      setLayout(new GridBagLayout()); 
      GridBagConstraints gbc = new GridBagConstraints(); 
      gbc.gridx = 0; 
      gbc.gridy = 0; 
      gbc.weightx = 1; 
      gbc.weighty = 1; 
      gbc.anchor = GridBagConstraints.CENTER; 
      content = new JPanel(new GridBagLayout()); 
      add(content, gbc); 

      JButton more = new JButton("More"); 
      more.addActionListener(new ActionListener() { 
       @Override 
       public void actionPerformed(ActionEvent e) { 
        GridBagConstraints gbc = new GridBagConstraints(); 
        gbc.gridx = 0; 
        gbc.gridy = 0; 

        content.removeAll(); 
        int count = 10 + (int) Math.round(Math.random() * 90); 
        System.out.println(count); 
        for (int index = 0; index < count; index++) { 
         gbc.gridx++; 
         if (index % 8 == 0) { 
          gbc.gridx = 0; 
          gbc.gridy++; 
         } 
         content.add(new JCheckBox(Integer.toString(index)), gbc); 
        } 

        content.revalidate(); 
        repaint(); 

       } 

      }); 

      gbc.gridy++; 
      gbc.weightx = 0; 
      gbc.weighty = 0; 

      add(more, gbc); 
     } 
    } 
}