Optimizing a dynamic JList

Question

Hi-
I have a JList that has a background thread dynamically adding entries to the ListModel. (it only adds, and always to the end of the list). It does this very quickly (many times per second), which causes the JList & its JScrollPane to flicker & reset its scroll position and also occasionally become unresponsive to input. Does anyone have ideas on how to control its refreshing so a) the scroll position does not reset and b) it queues up refreshes to once every 5 seconds or so?
I think I can handle b) from the thread that updates the ListModel, but am not sure about a). Thanks.
Carlos Hwa

Answer 1

Throttling down the update may have fixed your immediate problem, but the problem shouldn't be there at all.
I did not post some code because it is all written on an internal network & it is very difficult for us to transfer code to the internet.An SSCCE is not supposed to be your 'real code'. Didn't you read the page linked?
This is an SSCCE that adds an element to a JList every millisecond and still does not show any flicker or rescrolling.import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class DynamicList {
  JList list;
  int count;
  public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
      @Override
      public void run() {
        new DynamicList().makeUI();
  public void makeUI() {
    list = new JList(new DefaultListModel());
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 400);
    frame.setLocationRelativeTo(null);
    frame.add(new JScrollPane(list));
    frame.setVisible(true);
    new Timer(10, new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        ((DefaultListModel) list.getModel()).addElement("Item " + count++);
    }).start();
}Your problem is elsewhere in your code.
db