我创建了一个具有“自由设计”布局的JFrame（带有自动生成的代码）。在JFrame中，我有一个带有'null'布局的背景面板。后台面板包含另一个名为cardLayoutPanel的面板，该面板具有“cardlayout”设计。在卡片布局面板中，我有一个jScrollPane，它有一个名为firstNoteView的面板，它具有“自由设计”布局。在firstNoteView中，另一个名为NewNotePanel的面板具有“null”布局。
当我运行文件来运行程序时，jScrollPane（在卡布局面板中）工作，但是当我将自己的面板（使用我自己的代码）添加到firstNoteView时 - 在jScrollPane中，jScrollPane不起作用
下面是代码：
package interfaces;
import java.awt.Dimension;
import javax.swing.JPanel;
public class ScrollablePanel extends javax.swing.JFrame
{
Notes notes = new Notes ();
int numberOfNotes = 9;
int currentNoteNumber = 0;
//co-ordinates for first text area + used to calculate the rest of the text area locations
int x = 40;
int y = 100;
// panel sizes
int length = 250;
int breadth = 220;
int xgap = 310;
int ygap = 310;
// method to declare text areas for notes
public void createPanels () {
Dimension preferredSize = jScrollPane1.getPreferredSize();
JPanel[] panel = new JPanel [numberOfNotes];
System.out.println(numberOfNotes);
for (int construct = 0; construct < numberOfNotes; construct++)
panel [construct] = new JPanel ();
for (int setLocation = 1, xCordinate = 1, pHeight = 1; setLocation < numberOfNotes; setLocation++, xCordinate++) {
if ((setLocation < 4) && (setLocation != 0))
panel[setLocation].setBounds(x + (xgap * (setLocation)), y, length, breadth);
if ((setLocation % 4 == 0) && (setLocation != 0)) {
y = y + ygap;
x = 40;
xCordinate = 0;
firstNoteView.setBounds(200, 50, 1250, 850+(ygap*pHeight));
pHeight++;
}
if (setLocation >= 4)
panel[setLocation].setBounds(x + (xgap * (xCordinate)), y, length, breadth);
}
for (int add = 0; add < numberOfNotes; add++)
firstNoteView.add(panel[add]);
firstNoteView.repaint();
}
// method to hide neccessary components when for when the program initialises
public void setScreen ()
{
// setting components to be hidden, alphabetical order
firstNoteView.setVisible(true);
// remove all panels in the cardlayout
cardLayoutPanel.removeAll();
// add the firstNoteView Panel to set the default home screen
cardLayoutPanel.add(firstNoteView);
cardLayoutPanel.repaint();
}
public ScrollablePanel()
{
initComponents();
setScreen ();
setNumberOfNotes () ;
createPanels ();
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents()
{
BackgroundPanel = new javax.swing.JPanel();
cardLayoutPanel = new javax.swing.JPanel();
jScrollPane1 = new javax.swing.JScrollPane();
firstNoteView = new javax.swing.JPanel();
NewNotePanel = new javax.swing.JPanel();
lblNewNote = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setBounds(new java.awt.Rectangle(0, 23, 1440, 900));
setMinimumSize(new java.awt.Dimension(1440, 900));
setPreferredSize(new java.awt.Dimension(1440, 900));
BackgroundPanel.setBackground(new java.awt.Color(255, 255, 255));
BackgroundPanel.setLayout(null);
cardLayoutPanel.setLayout(new java.awt.CardLayout());
jScrollPane1.setBounds(new java.awt.Rectangle(0, 0, 1090, 0));
firstNoteView.setBackground(new java.awt.Color(0, 153, 204));
NewNotePanel.setLayout(null);
lblNewNote.setText("<html><center>+<br>New Note...</center></html>");
NewNotePanel.add(lblNewNote);
lblNewNote.setBounds(90, 90, 73, 32);
javax.swing.GroupLayout firstNoteViewLayout = new javax.swing.GroupLayout(firstNoteView);
firstNoteView.setLayout(firstNoteViewLayout);
firstNoteViewLayout.setHorizontalGroup(
firstNoteViewLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(firstNoteViewLayout.createSequentialGroup()
.addGap(40, 40, 40)
.addComponent(NewNotePanel, javax.swing.GroupLayout.PREFERRED_SIZE, 250, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(951, Short.MAX_VALUE))
);
firstNoteViewLayout.setVerticalGroup(
firstNoteViewLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(firstNoteViewLayout.createSequentialGroup()
.addGap(100, 100, 100)
.addComponent(NewNotePanel, javax.swing.GroupLayout.PREFERRED_SIZE, 220, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(792, Short.MAX_VALUE))
);
jScrollPane1.setViewportView(firstNoteView);
cardLayoutPanel.add(jScrollPane1, "card2");
BackgroundPanel.add(cardLayoutPanel);
cardLayoutPanel.setBounds(200, 60, 1240, 840);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(BackgroundPanel,
javax.swing.GroupLayout.DEFAULT_SIZE, 1440, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(BackgroundPanel, javax.swing.GroupLayout.DEFAULT_SIZE, 900, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
public static void main(String args[])
{
try
{
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels())
{
if ("Nimbus".equals(info.getName()))
{
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex)
{
java.util.logging.Logger.getLogger(ScrollablePanel.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex)
{
java.util.logging.Logger.getLogger(ScrollablePanel.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex)
{
java.util.logging.Logger.getLogger(ScrollablePanel.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex)
{
java.util.logging.Logger.getLogger(ScrollablePanel.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable()
{
public void run()
{
new ScrollablePanel().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JPanel BackgroundPanel;
private javax.swing.JPanel NewNotePanel;
private javax.swing.JPanel cardLayoutPanel;
private javax.swing.JPanel firstNoteView;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JLabel lblNewNote;
// End of variables declaration
}