我在使用JTextArea. 我的实际设置有所不同，但效果仍然存在。这是问题的图像：
当拥有者调整大小仅比他们的首选大小所需的JDialog1 个像素时，文本区域突然调整大小。JTextArea在我的实际设置中，它们突然变高了。我正在使用GridBagLayout，但它似乎发生在其他布局中。为什么是这样？
这是重现上述效果的易于编译的代码。
import java.awt.*;
import java.awt.event.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.*;
import javax.swing.text.JTextComponent;
public class TextDemo extends JDialog implements ActionListener {
private static final long serialVersionUID = -589374238138963529L;
protected JTextField textField;
protected JTextArea textArea;
private final static String newline = "\n";
private static final java.awt.Dimension SCREENSIZE =
java.awt.Toolkit.getDefaultToolkit().getScreenSize();
private static final java.awt.Point SCREENCENTER =
new java.awt.Point(SCREENSIZE.width/2,SCREENSIZE.height/2);
public TextDemo(Window owner, String shortMessage, String message, JComponent accessory) {
super(owner);
setTitle("Test");
setDefaultCloseOperation(JDialog.HIDE_ON_CLOSE);
Icon icon = UIManager.getIcon("OptionPane.warningIcon");
JTextArea shortText = makeMultiLineLabel(true);
shortText.setBorder(BorderFactory.createEtchedBorder());
shortText.setFont(shortText.getFont().deriveFont(Font.BOLD));
shortText.setRows(2);
shortText.setColumns(20);
shortText.setText(shortMessage);
JTextArea messageText = makeMultiLineLabel(true);
messageText.setBorder(BorderFactory.createEtchedBorder());
messageText.setFont(shortText.getFont().deriveFont(Font.PLAIN));
messageText.setRows(4);
messageText.setColumns(20);
messageText.setText(message);
JPanel buttonPanel = new JPanel();
buttonPanel.add(new JButton("OK"));
buttonPanel.add(new JButton("Cancel"));
JPanel contentPanel = new JPanel();
contentPanel.setOpaque(true);
contentPanel.setBorder(BorderFactory.createEmptyBorder(10, 10, 8, 9));
contentPanel.setLayout(new GridBagLayout());
GridBagConstraints c;
c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 0;
c.anchor = GridBagConstraints.FIRST_LINE_START;
c.gridheight = 2;
contentPanel.add(new JLabel(icon), c);
c = new GridBagConstraints();
c.gridx = 1;
c.gridy = 0;
c.fill = GridBagConstraints.BOTH;
c.weighty = 1.0;
c.weightx = 1.0;
contentPanel.add(shortText, c);
c = new GridBagConstraints();
c.gridx = 1;
c.gridy = 1;
c.fill = GridBagConstraints.BOTH;
c.weighty = 1.0;
c.weightx = 1.0;
contentPanel.add(messageText, c);
if (accessory != null) {
c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 2;
c.gridwidth = 2;
c.fill = GridBagConstraints.BOTH;
c.weighty = 1.0;
c.weightx = 1.0;
contentPanel.add(accessory, c);
}
c = new GridBagConstraints();
c.gridwidth = 2;
c.gridx = 0;
c.gridy = 3;
contentPanel.add(buttonPanel, c);
setContentPane(contentPanel);
}
public void actionPerformed(ActionEvent evt) {
String text = textField.getText();
textArea.append(text + newline);
textField.selectAll();
//Make sure the new text is visible, even if there
//was a selection in the text area.
textArea.setCaretPosition(textArea.getDocument().getLength());
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event dispatch thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("TextDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
try {
throw new Exception("Test");
} catch (Exception e) {
TextDemo t = new TextDemo(frame, "You won't get away with this!",
"Alert! Alert! A chocy nut bar has been removed without payment!" +
" A chocy nut bar... has been REMOVED! WITHOUT PAYMENT! Alert, alert!",
getStackTraceTextArea(e));
//Display the window.
frame.pack();
frame.setLocation(SCREENCENTER.x - frame.getSize().width/2,
SCREENCENTER.y - frame.getSize().height/2);
frame.setVisible(true);
t.setModal(true);
t.pack();
t.setLocation(getPos(t, t.getOwner()));
t.setVisible(true);
}
}
protected static JComponent getStackTraceTextArea(Throwable exception) {
JTextArea textArea = new JTextArea();
textArea.setEditable(false);
textArea.setLineWrap(false);
textArea.append(getTraceMessage(exception));
textArea.setCaretPosition(0);
JScrollPane scroll = new JScrollPane(textArea);
scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scroll.setPreferredSize(new Dimension(50, 140));
return scroll;
}
private static final String getTraceMessage(Throwable exception) {
StringBuilder out = new StringBuilder((new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"))
.format(new Date())+": Unhandled Exception: \n"
+exception.toString()+"\n\nStack Trace:\n");
StackTraceElement[] stackTrace = exception.getStackTrace();
for (int i = 0; i < stackTrace.length; i++) {
String toAppend = stackTrace[i].toString();
if (i != stackTrace.length-1) toAppend += "\n";
out.append(toAppend);
}
return out.toString();
}
public static final JTextArea makeMultiLineLabel(boolean selectable) {
JTextArea area = new JTextArea();
area.setWrapStyleWord(true);
area.setLineWrap(true);
area.setFont(UIManager.getFont("Label.font"));
area.setEditable(false);
area.setCursor(null);
area.setOpaque(false);
area.setFocusable(selectable);
area.setAlignmentX(JTextComponent.LEFT_ALIGNMENT);
area.setMinimumSize(new Dimension(0,0));
return area;
}
private static Point getPos(JDialog d, Window w) {
return new Point(w.getX()+(w.getWidth ()-d.getWidth ())/2,
w.getY()+(w.getHeight()-d.getHeight())/2);
}
public static void main(String[] args) {
//Schedule a job for the event dispatch thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
编辑建议实施一些更改，问题仍然存在：
