Problems with dynamic resize of JTextPane...

Question

Dear Java Gurus,
I am quite new to Java, so I am strill struggling to understand the details about it all...but thanks
to a lot of very helpful people in this forum, the bits and pieces start to come together, even
though it's obvious that I now need guidance again :-)
I posted yesterday regarding how I could implement a JTextPane that dynamically would change
its height. This means that the JTextPane has a fixed width, but when the user types in text, its sets
its own height to fit the enterred text. A very kind person posted some code that more or less looks
like the code below, with a few changes:
package test;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import java.awt.*;
public class test {   
  public static void main(String[] argv)
    final JFrame frame = new JFrame();           
    JTextPane pane= new JTextPane("Test ");           
    pane.getDocument().addDocumentListener(new DocumentListener()
      public void insertUpdate(DocumentEvent e) {proccess(e.getDocument());}         
      public void removeUpdate(DocumentEvent e) {proccess(e.getDocument());}         
      public void changedUpdate(DocumentEvent e) {proccess(e.getDocument());}   
      private void proccess(Document doc)
        Dimension size = pane.getPreferredSize();     
        pane.setSize(150, (int)size.getHeight());    
        frame.validate();    
    frame.getContentPane().add(new JScrollPane(pane), BorderLayout.SOUTH);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);      
    frame.setSize(400, 300);       
    frame.setLocationRelativeTo(null);       
    frame.setVisible(true);   
}The code works just fine, but has a small "feature" in it that I don't understand. It appears
like the resizing has a delay in it. If you enter the JTextPane and press return once, the text
pane will not resize. If you press backspace, the cursor will move back up, but now the
text pane will increase its size, to fit the size of the previos text size. If you now press the
return key again, the text pane shrinks by one line.
In other words...it seems the resizing is always delayed by one, as if the last entered
character is not taken into account when preferredSize() returns the value. As I don't yet
understand in which order events are generated and handled, does anybody see what I
need to change in order to get rid of this slightly disturbing delay? :-)
Any comments would be highly appreciated!
Best regards,
Xxodus.

Answer 1

You try to ask size before edition process is complete.
Try to change size after finishing processing of document change event.
Like this.
      private void proccess(Document doc)
          SwingUtilities.invokeLater(new Runnable() {
              public void run() {
                  Dimension size = pane.getPreferredSize();
                  pane.setSize(150, (int)size.getHeight());
                  frame.validate();
      }regards,
Stas