通过删除与该问题无关的所有代码，我简化了我的问题。这给我留下了2个简单的Java类：
BugFrameTest。存储最初为null的DefaultStyledDocument。有一个按钮，它打开一个对话框，第二个类。
import java.awt.Dimension;
import java.awt.Toolkit;
import javax.swing.text.DefaultStyledDocument;
import javax.swing.text.StyledDocument;
public class BugFrameTest extends javax.swing.JFrame {
private DefaultStyledDocument sectionTextDoc = null;
public BugFrameTest() {
initComponents();
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jButton1 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jButton1.setText("Click for Dialog");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
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(jButton1)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(22, 22, 22)
.addComponent(jButton1)
.addContainerGap(20, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// java - get screen size using the Toolkit class
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
double screenWidth = screenSize.getWidth();
double screenHeight = screenSize.getHeight();
double percentReduce = 0.90;
Dimension dimension = new Dimension();
dimension.setSize(
(int) (screenWidth * percentReduce),
(int) (screenHeight * percentReduce));
SectionJDialog2 sectionJDialog2 = null;
sectionJDialog2 = new SectionJDialog2(
this, true, sectionTextDoc);
sectionJDialog2.setLocationRelativeTo(this);
sectionJDialog2.setVisible(true);
// After closing we store the document to display again.
sectionTextDoc
= (DefaultStyledDocument) sectionJDialog2.getDocument();
}
/**
* @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(BugFrameTest.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(BugFrameTest.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(BugFrameTest.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(BugFrameTest.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 BugFrameTest().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
// End of variables declaration
}
SectionJDialog2。该对话框包含一个JTextPane和一个按钮，该按钮将一个空的JTextArea插入JTextPane中。关闭对话框时，JTextPane的DefaultStyledDocument存储在BugFrameTest中。
import java.awt.Color;
import javax.swing.JTextArea;
import javax.swing.text.DefaultStyledDocument;
public class SectionJDialog2 extends javax.swing.JDialog {
private DefaultStyledDocument doc = new DefaultStyledDocument();
public SectionJDialog2(
java.awt.Frame parent,
boolean modal,
DefaultStyledDocument doc) {
super(parent, modal);
initComponents();
pack();
if (doc == null) {
doc = new DefaultStyledDocument();
}
this.jTextPane1.setDocument(doc);
}
public DefaultStyledDocument getDocument() {
return (DefaultStyledDocument) this.jTextPane1.getDocument();
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jScrollPane2 = new javax.swing.JScrollPane();
jTextPane1 = new javax.swing.JTextPane();
textAreaButton = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);
addWindowListener(new java.awt.event.WindowAdapter() {
public void windowClosed(java.awt.event.WindowEvent evt) {
closeDialogHandler(evt);
}
public void windowClosing(java.awt.event.WindowEvent evt) {
formWindowClosing(evt);
}
});
jScrollPane2.setViewportView(jTextPane1);
textAreaButton.setText("Insert Text Area");
textAreaButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
textAreaButtonActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane2, javax.swing.GroupLayout.DEFAULT_SIZE, 551, Short.MAX_VALUE)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(textAreaButton)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap()
.addComponent(textAreaButton)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 251, javax.swing.GroupLayout.PREFERRED_SIZE))
);
pack();
}// </editor-fold>
private void closeDialogHandler(java.awt.event.WindowEvent evt) {
}
private void formWindowClosing(java.awt.event.WindowEvent evt) {
this.dispose();
}
private void textAreaButtonActionPerformed(java.awt.event.ActionEvent evt) {
JTextArea quoteField = new JTextArea();
quoteField.setBackground(Color.lightGray);
quoteField.setLineWrap(true);
jTextPane1.insertComponent(quoteField);
}
// Variables declaration - do not modify
private javax.swing.JScrollPane jScrollPane2;
private javax.swing.JTextPane jTextPane1;
private javax.swing.JButton textAreaButton;
// End of variables declaration
}
第一次打开SectionJDialog2时，一切都很好。您可以插入JTextArea和没有问题的文本。然后关闭对话框。
在重新打开SectionJDialog2时（通过在BugFrameTest中按下按钮），文本和JTextArea仍然存在。但是，如果现在在JTextArea之后立即按返回键，则JTextArea消失（至少从显示中消失）。您可以关闭并重新打开对话框，然后重新出现JTextArea。
那么我的问题就是，如何阻止JTextArea消失？
提前致谢。
最佳答案
如果没有JScrollPane父级，则不应使用JTextArea。如果没有该父项，它希望尽可能宽，这会导致JTextPane的布局问题。
JTextArea是一个文本组件，它允许多行文本。那真的是你想要的吗？如果只需要单行文本组件，则应使用JTextField。
如果您坚持使用JTextArea set its preferred column count，并将其放置在JScrollPane中：
JTextArea quoteField = new JTextArea();
quoteField.setColumns(10);
quoteField.setBackground(Color.lightGray);
quoteField.setLineWrap(true);
jTextPane1.insertComponent(new JScrollPane(quoteField));