我有一个 Swing GUI 挑战，我已经提炼到以下 SSCCE。问题在于，在更新窗口底部的 JLabel 以反射(reflect)所选节点时，JTree/JScrollPane 会以令人不安的方式跳来跳去。
查看此行为的最佳方式是运行 SSCCE，单击 JTree，并按住键盘的向下箭头以快速遍历 JTree。 GUI 闪烁，就好像 JLabel 被删除然后再次添加一样。但事实并非如此——我只是在更新 JLabel 的文本。
我想控制 GUI 的重绘，使其不那么刺耳。我需要保留“状态栏”的自动换行和动态高度——使用固定高度的组件可以解决跳跃问题，但违背了设计理念。
我已经尝试了几种不同的方法来更新“状态栏”区域(您可以在 SSCCE 的 TreeSelectionListener 中看到注释掉的方法之一)，但是我尝试过的所有方法要么导致高度重新计算不正确，要么导致闪烁.
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;
public class JTreePlusStatus extends JFrame {
JPanel _contentPane;
JScrollPane _jScrollPane;
JTree _jTree;
JLabel _jLabelDescription;
GridBagConstraints _gbcJLabelDescription;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
String sysLaf = UIManager.getSystemLookAndFeelClassName();
UIManager.setLookAndFeel(sysLaf);
JFrame frame = new JTreePlusStatus();
frame.setSize(300, 300);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public JTreePlusStatus() {
initComponents();
initCustom();
}
void initComponents() {
// Boilerplate layout busywork
_contentPane = new JPanel();
GridBagLayout gblContentPane = new GridBagLayout();
_contentPane.setLayout(gblContentPane);
setContentPane(_contentPane);
_jScrollPane = new JScrollPane();
GridBagConstraints gbcJScrollPane = new GridBagConstraints();
gbcJScrollPane.fill = GridBagConstraints.BOTH;
gbcJScrollPane.weighty = 1.0;
gbcJScrollPane.weightx = 1.0;
gbcJScrollPane.gridx = 0;
gbcJScrollPane.gridy = 0;
_contentPane.add(_jScrollPane, gbcJScrollPane);
_jTree = new JTree();
_jScrollPane.setViewportView(_jTree);
_jTree.addTreeSelectionListener(new TreeSelectionListenerImpl());
_jLabelDescription = new JLabel(" ");
_gbcJLabelDescription = new GridBagConstraints();
_gbcJLabelDescription.fill = GridBagConstraints.HORIZONTAL;
_gbcJLabelDescription.gridx = 0;
_gbcJLabelDescription.gridy = 1;
_contentPane.add(_jLabelDescription, _gbcJLabelDescription);
}
void initCustom() {
// Set sample data onto the JTree
_jTree.setModel(createSampleModel());
// Expand entire tree
for (int i = 0; i < _jTree.getRowCount(); i++) {
_jTree.expandRow(i);
}
}
public DefaultTreeModel createSampleModel() {
DefaultMutableTreeNode top = new DefaultMutableTreeNode("Music");
for (int i = 0; i < 100; i++) {
String s = "Classical - Concertos - Beethoven "
+ "- S No. 5 - E-Flat Major " + i;
top.add(new DefaultMutableTreeNode(s));
}
DefaultTreeModel defaultTreeModel = new DefaultTreeModel(top);
return defaultTreeModel;
}
class TreeSelectionListenerImpl implements TreeSelectionListener {
public void valueChanged(TreeSelectionEvent e) {
TreePath selectionPath = _jTree.getSelectionPath();
String s = selectionPath.getLastPathComponent().toString();
String newText = "<html><b>Name:</b> " + s
+ " <br><b>Description: </b>" + s + "</html>";
/** Tried this -- causes the JTree to jump around */
_jLabelDescription.setText(newText);
/**
* OK, try making a new JLabel and "set" it into the parent,
* hoping that there won't be an intermediate state where label's
* space in the GUI collapses temporarily
*/
//final JLabel newJLabel = new JLabel(newText);
//final Container parent = _jLabelDescription.getParent();
//parent.add(newJLabel, _gbcJLabelDescription, 1);
//parent.remove(_jLabelDescription);
//if (parent instanceof JComponent) {
// JComponent jc = (JComponent) parent;
// jc.validate(); // must revalidate after adding or removing
//}
//_jLabelDescription = newJLabel;
// No luck, JTree/JScrollPane still jumps around
}
}
}
最佳答案
使用 JTextPane 而不是 JLabel 时似乎工作正常:
_jLabelDescription = new JTextPane();
_jLabelDescription.setContentType( "text/html" );
关于java - 控制 HTML JLabel 的重新验证，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19554631/