我有一个带有 VerticalLayout (org.jdesktop.swingx.VerticalLayout) 的 mainPanel。主面板有几个子面板。其中之一是根据用户选择动态变化的面板。因此，我将其布局设置为 CardLayout，我认为这是实现该目标的最简单(也许是最好的？)方法。
我将该面板称为 elasticPanel。顾名思义，它应该是有弹性的。这意味着，它应该能够扩展和收缩。假设它的行为是这样的。如果用户选择 1，elasticPanel 应该显示一个，比如 JComboBox。如果用户选择 2，则两个 JComboBox...
好的，到现在为止一切正常。现在，当 elasticPanel 显示两个 JComboBox 时，用户再次选择 1。我现在需要做的是 elasticPanel 应该显示一个正常大小的 JComboBox。但是由于 elasticPanel 已经展开，所以它显示 JComboBox 已拉伸(stretch)以适应它的大小。所以它给人一种奇怪的感觉。
以下屏幕截图显示了我在界面上遇到的问题。
选择之前。 NONE 被选中。
一个元素被选中
NONE 再次被选中
我需要最后一个屏幕截图中的 elasticPanel(故障位置)与第一个屏幕截图中的一样。这只是一个简单的案例。想象一下在显示大约 5、6 个子组件后返回到 NONE 时的样子。
我试过 setSize() 方法。它什么也没做..那么如何解决这个问题呢？
感谢任何帮助。谢谢!
最佳答案
很难说您指的是 CardLayout 是什么东西。自 CardLayout以不同的方式工作。你可以做的就是简单地放置一个 JPanel 说 basePanel 有 GridLayout(0, 1) 然后放置这个 JPanel在另一个 JPanel 之上说 contentPanel，现在将其设置为 JFrame 的内容 Pane ，并在添加或删除时调用 pack() View 中的一个元素。这是一个向您展示我的意思的示例。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ElasticPanel
{
private JFrame frame;
private JPanel contentPane;
private JPanel basePanel;
/*
* Array to hold the JComboBox
* elements.
*/
private JComboBox[] prodCombo;
private JComboBox[] temp;
/*
* Counter to keep track
* of the number of JComboBox
* present.
*/
private int counter;
/*
* Data for each JComboBox
*/
private String[] data = {
"None",
"Sub Category"
};
private ActionListener comboAction =
new ActionListener()
{
@Override
public void actionPerformed(ActionEvent ae)
{
JComboBox cbox = (JComboBox) ae.getSource();
String command = (String) ae.getActionCommand();
int index = Integer.parseInt(command);
String selection = (String) cbox.getSelectedItem();
if (selection.equals("None"))
{
/*
* i = index + 1, because, we want to
* remove all JComboBox after this one.
*/
for (int i = (index + 1); i < prodCombo.length; i++)
{
temp = new JComboBox[prodCombo.length];
for (int j = 0; j < prodCombo.length; j++)
temp[j] = prodCombo[j];
basePanel.remove(prodCombo[i]);
}
prodCombo = new JComboBox[index + 1];
for (int i = 0; i <= index; i++)
{
prodCombo[i] = temp[i];
}
counter = prodCombo.length;
System.out.println("Item Removed\nCounter : " + counter);
}
else if (selection.equals("Sub Category"))
{
counter++;
temp = new JComboBox[counter];
for (int i = 0; i < prodCombo.length; i++)
{
temp[i] = prodCombo[i];
}
temp[counter - 1] = new JComboBox(data);
temp[counter - 1].setActionCommand("" + (counter - 1));
temp[counter - 1].addActionListener(this);
prodCombo = new JComboBox[counter];
for (int i = 0; i < counter; i++)
prodCombo[i] = temp[i];
basePanel.add(prodCombo[counter - 1]);
System.out.println("Item Added\nCounter : " + counter);
}
//basePanel.revalidate();
//basePanel.repaint();
frame.pack();
}
};
public ElasticPanel()
{
prodCombo = new JComboBox[1];
counter = 1;
}
private void displayGUI()
{
frame = new JFrame("Elastic Panel Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = new JPanel();
basePanel = new JPanel(new GridLayout(0, 1, 5, 5));
prodCombo[counter - 1] = new JComboBox(data);
prodCombo[counter - 1].setActionCommand("" + (counter - 1));
prodCombo[counter - 1].addActionListener(comboAction);
basePanel.add(prodCombo[counter - 1]);
contentPane.add(basePanel);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
new ElasticPanel().displayGUI();
}
});
}
}
*最新更新:*
通过添加更多组件并将弹性面板放在其他位置而不是内容 Pane 顶部来获得更多洞察力。
import java.awt.*;
import java.awt.event.*;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.*;
public class VirtualViewGUI extends JFrame
{
private JPanel rightPanel;
private ElasticPanel elasticPanel;
public VirtualViewGUI()
{
super("Virtual View");
JMenuBar jmenuBar = new JMenuBar();
JMenu fileMenu = new JMenu("File");
JMenu helpMenu = new JMenu("Help");
JMenu feel = new JMenu("Look & Feel");
JMenu layOutMenu = new JMenu("ConfigureCells");
JMenuItem add_files = new JMenuItem("Select Directory..");
JMenuItem minCellSize = new JMenuItem("height 260 X width 260");
JMenuItem moderateCellSize = new JMenuItem("height 320 X width 320");
JMenuItem maxCellSize = new JMenuItem("height 360 X width 360");
JMenuItem exit = new JMenuItem("Exit");
JMenuItem help = new JMenuItem("Help Content");
fileMenu.add(add_files);
fileMenu.add(exit);
layOutMenu.add(minCellSize);
layOutMenu.add(moderateCellSize);
layOutMenu.add(maxCellSize);
helpMenu.add(help);
jmenuBar.add(fileMenu);
jmenuBar.add(layOutMenu);
jmenuBar.add(helpMenu);
ImageIcon myImage = null;
try
{
myImage = new ImageIcon(
new URL("http://gagandeepbali.uk.to/" +
"gaganisonline/images/swing/" +
"stackoverflow/cow-cartoon.jpg"));
}
catch(MalformedURLException mue)
{
mue.printStackTrace();
}
JLabel icon = new JLabel(myImage);
icon.setIcon(myImage);
setJMenuBar(jmenuBar);
rightPanel = new JPanel();
elasticPanel = new ElasticPanel(this);
rightPanel.add(elasticPanel);
JPanel contentPane = new JPanel();
contentPane.setLayout(new BorderLayout(5, 5));
contentPane.add(icon, BorderLayout.CENTER);
contentPane.add(rightPanel, BorderLayout.LINE_END);
setContentPane(contentPane);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationByPlatform(true);
setVisible(true);
System.out.println("File Separator is : " + System.getProperty("file.separator"));
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
new VirtualViewGUI();
}
});
}
}
class ElasticPanel extends JPanel
{
private JFrame frame;
private JPanel contentPane;
/*
* Array to hold the JComboBox
* elements.
*/
private JComboBox[] prodCombo;
private JComboBox[] temp;
/*
* Counter to keep track
* of the number of JComboBox
* present.
*/
private int counter;
/*
* Data for each JComboBox
*/
private String[] data = {
"None",
"Sub Category"
};
private ActionListener comboAction =
new ActionListener()
{
@Override
public void actionPerformed(ActionEvent ae)
{
JComboBox cbox = (JComboBox) ae.getSource();
String command = (String) ae.getActionCommand();
int index = Integer.parseInt(command);
String selection = (String) cbox.getSelectedItem();
if (selection.equals("None"))
{
/*
* i = index + 1, because, we want to
* remove all JComboBox after this one.
*/
for (int i = (index + 1); i < prodCombo.length; i++)
{
temp = new JComboBox[prodCombo.length];
for (int j = 0; j < prodCombo.length; j++)
temp[j] = prodCombo[j];
remove(prodCombo[i]);
}
prodCombo = new JComboBox[index + 1];
for (int i = 0; i <= index; i++)
{
prodCombo[i] = temp[i];
}
counter = prodCombo.length;
System.out.println("Item Removed\nCounter : " + counter);
}
else if (selection.equals("Sub Category"))
{
counter++;
temp = new JComboBox[counter];
for (int i = 0; i < prodCombo.length; i++)
{
temp[i] = prodCombo[i];
}
temp[counter - 1] = new JComboBox(data);
temp[counter - 1].setActionCommand("" + (counter - 1));
temp[counter - 1].addActionListener(this);
prodCombo = new JComboBox[counter];
for (int i = 0; i < counter; i++)
prodCombo[i] = temp[i];
add(prodCombo[counter - 1]);
System.out.println("Item Added\nCounter : " + counter);
}
//revalidate();
//repaint();
frame.pack();
}
};
public ElasticPanel(JFrame frame)
{
this.frame = frame;
prodCombo = new JComboBox[1];
counter = 1;
setLayout(new GridLayout(0, 1, 5, 5));
prodCombo[counter - 1] = new JComboBox(data);
prodCombo[counter - 1].setActionCommand("" + (counter - 1));
prodCombo[counter - 1].addActionListener(comboAction);
add(prodCombo[counter - 1]);
}
}
关于java - 如何契约(Contract)卡布局，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12659763/