我在Netbeans 8.1（Java版本1.8.0_65）中编写了一个简单的程序，它在其中获取已发现文件的列表并将它们写入jTextArea。这种方法很好，除非有很多行写入jTextArea（即超过500行左右），滚动条中的拇指消失。我看到了post描述的确切问题。
这似乎是带有Nimbus L＆amp; F的known issue，并且人们已经发布了相关的解决方法，如上文所述，他们说要解决这个问题只是添加一行：
UIManager.getLookAndFeelDefaults().put("ScrollBar.minimumThumbSize", new Dimension(30, 30));
我遇到的问题是我在哪里放置这行代码？我已经尝试在创建jScrollPanel之前将它添加到initComponents（如下面的代码所示）。在检查Nimbus是否可用时，我也在if语句之后尝试了它：
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
我显然只是试图在不了解我正在做的事情的情况下坚持不同的地方，并且毫不奇怪，这是不起作用。
有人可以帮我确定这个解决方法的代码行吗？
我的代码：
public class ViewFiles extends javax.swing.JFrame {
/**
* Creates new form ViewFiles
*/
public ViewFiles() {
initComponents();
}
public ViewFiles(ArrayList<DiscoveredFile> files){
initComponents();
discoveredFiles = files;
displayFiles();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
javax.swing.UIManager.getLookAndFeelDefaults().put("Scrollbar.minimumThumbSize", new Dimension(30,30));
jScrollPane1 = new javax.swing.JScrollPane();
viewFilesTextArea = new javax.swing.JTextArea();
viewFilesCloseButton = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
viewFilesTextArea.setColumns(20);
viewFilesTextArea.setRows(5);
jScrollPane1.setViewportView(viewFilesTextArea);
viewFilesCloseButton.setText("Close");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 656, Short.MAX_VALUE)
.addContainerGap())
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(viewFilesCloseButton)
.addGap(29, 29, 29))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 277, Short.MAX_VALUE)
.addGap(18, 18, 18)
.addComponent(viewFilesCloseButton)
.addContainerGap())
);
pack();
}// </editor-fold>
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
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(ViewFiles.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(ViewFiles.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(ViewFiles.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(ViewFiles.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 ViewFiles().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JButton viewFilesCloseButton;
private javax.swing.JTextArea viewFilesTextArea;
// End of variables declaration
private ArrayList<DiscoveredFile> discoveredFiles;
public void displayFiles() {
for (DiscoveredFile file : discoveredFiles){
viewFilesTextArea.append(file.getFullPath() + "\n");
}
}
}
答案 0 :(得分：1)
这是另一种方法：
UIDefaults def = new UIDefaults();
def.put("ScrollBar.minimumThumbSize", new Dimension(30, 30));
jScrollPane1 = new JScrollPane();
jScrollPane1.getVerticalScrollBar().putClientProperty("Nimbus.Overrides", def);
import java.awt.*;
import java.util.*;
import javax.swing.*;
public class ViewFiles2 extends JFrame {
private JScrollPane jScrollPane1;
private JButton viewFilesCloseButton;
private JTextArea viewFilesTextArea;
public ViewFiles2() {
initComponents();
displayFiles();
}
private void initComponents() {
//NG?: UIManager.getLookAndFeelDefaults().put("ScrollBar.minimumThumbSize", new Dimension(30, 30));
//OK?: UIManager.getDefaults().put("ScrollBar.minimumThumbSize", new Dimension(30, 30));
jScrollPane1 = new JScrollPane();
UIDefaults def = new UIDefaults();
def.put("ScrollBar.minimumThumbSize", new Dimension(30, 30));
jScrollPane1.getVerticalScrollBar().putClientProperty("Nimbus.Overrides", def);
viewFilesTextArea = new JTextArea(20, 5);
viewFilesCloseButton = new JButton("Close");
jScrollPane1.setViewportView(viewFilesTextArea);
GroupLayout layout = new GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, GroupLayout.DEFAULT_SIZE, 656, Short.MAX_VALUE)
.addContainerGap())
.addGroup(GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(viewFilesCloseButton)
.addGap(29, 29, 29))
);
layout.setVerticalGroup(
layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, GroupLayout.DEFAULT_SIZE, 277, Short.MAX_VALUE)
.addGap(18, 18, 18)
.addComponent(viewFilesCloseButton)
.addContainerGap())
);
setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
pack();
}
public void displayFiles() {
viewFilesTextArea.setText(String.join("\n", Collections.nCopies(500, "aaaaaaaaaaaaa")));
}
public static void main(String[] args) {
try {
for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
//OK?: UIManager.getLookAndFeelDefaults().put("ScrollBar.minimumThumbSize", new Dimension(30, 30));
//NG?: UIManager.getDefaults().put("ScrollBar.minimumThumbSize", new Dimension(30, 30));
EventQueue.invokeLater(() -> {
new ViewFiles2().setVisible(true);
});
}
}