我目前正在为 JComboBox
编写自定义 ListCellRenderer
。为此,我使用一个系统在 L&F 更改时获取新的渲染器,并将方法委托(delegate)给它。这在所有 L&F 中都很有效。但是,当我将此组件放置在面板中(以便我可以添加更多组件)时,它在 Metal 和 Windows L&F 中运行良好,但 JComboBox
文本在 Motif 中消失。查看截图和代码:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TextDemo extends JPanel implements ActionListener {
private static JFrame frame;
public TextDemo() {
super(new GridBagLayout());
JComboBox correct = new JComboBox(new String[]{"One", "Two", "Three"});
JComboBox alsoCorrect = new JComboBox(new String[]{"One", "Two", "Three"});
alsoCorrect.setRenderer(new MyRenderer());
JComboBox incorrect = new JComboBox(new String[]{"One", "Two", "Three"});
incorrect.setRenderer(new NotWorkingRenderer());
JButton button = new JButton("Change LnF");
button.addActionListener(this);
add(correct, getConstraints(0));
add(alsoCorrect, getConstraints(1));
add(incorrect, getConstraints(2));
add(button, getConstraints(3));
}
private GridBagConstraints getConstraints(int y) {
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0; c.gridy = y;
c.insets = new Insets(4,8,4,8);
c.weightx = 1.0; c.weighty = 1.0;
c.fill = GridBagConstraints.HORIZONTAL;
c.anchor = GridBagConstraints.FIRST_LINE_START;
return c;
}
@Override
public void actionPerformed(ActionEvent ev) {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.motif.MotifLookAndFeel");
SwingUtilities.updateComponentTreeUI(frame);
} catch (Exception ex) {
ex.printStackTrace();
}
}
private static void createAndShowGUI() {
frame = new JFrame("TextDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TextDemo());
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
class MyRenderer implements ListCellRenderer {
protected static ListCellRenderer delegate;
static {
refreshRenderers();
UIManager.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals("lookAndFeel")) {
refreshRenderers();
}
}
});
}
protected static void refreshRenderers() {
delegate = new JComboBox().getRenderer();
}
@Override
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
return delegate.getListCellRendererComponent(list, value,
index, isSelected, cellHasFocus);
}
}
class NotWorkingRenderer extends MyRenderer {
private JPanel panel = new JPanel();
public NotWorkingRenderer() {
panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
}
@Override
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
Component c = super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
c.setMaximumSize(new Dimension(Short.MAX_VALUE, Short.MAX_VALUE));
panel.removeAll();
panel.add(c);
return panel;
}
}
任何有关理解为什么会发生这种情况的帮助将不胜感激!
最佳答案
不是答案,
但是看看会发生什么,使用 JPanel 作为 JComboBox 的渲染器 JComponent
您确定使用字符串值的 JPanel 是正确的方法吗?请问目标是什么,
用默认的JLabel、(J)Component代替JPanel是否有同样的效果
来自代码
import java.awt.*;
import java.awt.event.*;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.*;
public class TextDemo extends JPanel implements ActionListener {
private static JFrame frame;
public TextDemo() {
super(new GridBagLayout());
JComboBox correct = new JComboBox(new String[]{"One", "Two", "Three"});
JComboBox alsoCorrect = new JComboBox(new String[]{"One", "Two", "Three"});
alsoCorrect.setRenderer(new MyRenderer());
JComboBox incorrect = new JComboBox(new String[]{"One", "Two", "Three"});
incorrect.setRenderer(new NotWorkingRenderer());
JButton button = new JButton("Change LnF");
button.addActionListener(this);
add(incorrect, getConstraints(0));
add(correct, getConstraints(1));
add(alsoCorrect, getConstraints(2));
add(button, getConstraints(3));
}
private GridBagConstraints getConstraints(int y) {
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = y;
c.insets = new Insets(4, 8, 4, 8);
c.weightx = 1.0;
c.weighty = 1.0;
c.fill = GridBagConstraints.HORIZONTAL;
c.anchor = GridBagConstraints.FIRST_LINE_START;
return c;
}
@Override
public void actionPerformed(ActionEvent ev) {
try {
UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
SwingUtilities.updateComponentTreeUI(frame);
} catch (Exception ex) {
ex.printStackTrace();
}
}
private static void createAndShowGUI() {
frame = new JFrame("TextDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TextDemo());
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.motif.MotifLookAndFeel");
//SwingUtilities.updateComponentTreeUI(frame);
} catch (Exception ex) {
ex.printStackTrace();
}
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
}
}
class MyRenderer implements ListCellRenderer {
protected static ListCellRenderer delegate;
static {
refreshRenderers();
UIManager.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals("lookAndFeel")) {
refreshRenderers();
}
}
});
}
protected static void refreshRenderers() {
delegate = new JComboBox().getRenderer();
}
@Override
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
return delegate.getListCellRendererComponent(list, value,
index, isSelected, cellHasFocus);
}
}
class NotWorkingRenderer extends MyRenderer {
private JPanel panel = new JPanel();
public NotWorkingRenderer() {
panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
}
@Override
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
Component c = super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
c.setMaximumSize(new Dimension(Short.MAX_VALUE, Short.MAX_VALUE));
panel.add(c);
return panel;
}
}
EDIT_1。
除 ModifL&F 之外的所有标准 L&F 均正确显示
向前迈出一步???,代码行
in Correct.setEditable(true);
生成
- 我不知道 ModifL&F 和 non_editable JComboBox 的正确方法
EDIT_2nd。
我瞎了
class NotWorkingRenderer extends MyRenderer {
, pip... pip... pip...phaaa 我从未
添加
/删除
/修改
JComponent
在Xxx(Xxx)Renderer
中,但是是关于是否可能,
class NotWorkingRenderer extends BasicComboBoxRenderer {
private JPanel panel = new JPanel();
public NotWorkingRenderer() {
panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
//panel.setOpaque(false);
}
@Override
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
JLabel c = (JLabel) super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
c.setMaximumSize(new Dimension(Short.MAX_VALUE, Short.MAX_VALUE));
panel.removeAll();
panel.add(c);
panel.revalidate();
panel.repaint();
return panel;
}
}
关于Java Swing - Motif L&F 中自定义组合框渲染器中的文本消失,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18536082/