FULL PRODUCT VERSION :
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Client VM (build 1.6.0-b105, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
As bug# 4075484 which was in the java.awt.ScrollPane, the same thing happened with me using the JScrollBar class. It always returned TRACK when I want to get the action type that occurred on the Jscrollbar. The same fix of the java.awt.Scrollbar class must be populated to the javax.swing.JScrollBar class

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
create an object of the below class and pass it in the addAdjustmentListener(AdjustmentListener listener) method of the JScrollBar.

class VScrollListener implements AdjustmentListener {

    public void adjustmentValueChanged(java.awt.event.AdjustmentEvent evt) {
        int type = evt.getAdjustmentType();
        switch (type) {
            case AdjustmentEvent.UNIT_INCREMENT:
               
                JOptionPane.showMessageDialog(null, "UI");
                break;
            case AdjustmentEvent.UNIT_DECREMENT:
             
                JOptionPane.showMessageDialog(null, "UD");
                break;
            case AdjustmentEvent.BLOCK_INCREMENT:
              
                JOptionPane.showMessageDialog(null, "BLOCK_INCREMENTI");
                break;
            case AdjustmentEvent.BLOCK_DECREMENT:
            
                JOptionPane.showMessageDialog(null, "BLOCK_DECREMENT");
                break;
            case AdjustmentEvent.TRACK:
         
                JOptionPane.showMessageDialog(null, "TRACK");
                break;

      

        }

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
to display a different message depending on the action on the scrollbar
ACTUAL -
it always gives TRACK

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
Same as bug# 4075484
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
use the fix of bug# 4075484 : use java.awt.Scrollbar class instead of javax.swing.JScrollBar class.