FULL PRODUCT VERSION :
java version "1.5.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64)
Java HotSpot(TM) Client VM (build 1.5.0-b64, mixed mode)

FULL OPERATING SYSTEM VERSION :
Microsoft Windows XP

A DESCRIPTION OF THE PROBLEM :
Run attached test and select any tab in the JTabbedPane
you'll get the following exception

java.lang.NullPointerException
at javax.swing.plaf.basic.BasicTabbedPaneUI.scrollableTabLayoutEnabled(BasicTabbedPaneUI.java:246)
at javax.swing.plaf.basic.BasicTabbedPaneUI.access$400(BasicTabbedPaneUI.java:37)
at javax.swing.plaf.basic.BasicTabbedPaneUI$Handler.stateChanged(BasicTabbedPaneUI.java:3504)
at javax.swing.JTabbedPane.fireStateChanged(JTabbedPane.java:312)
at javax.swing.JTabbedPane$ModelListener.stateChanged(JTabbedPane.java:244)
at javax.swing.DefaultSingleSelectionModel.fireStateChanged(DefaultSingleSelectionModel.java:116)
at javax.swing.DefaultSingleSelectionModel.setSelectedIndex(DefaultSingleSelectionModel.java:50)

EXPECTED VERSUS ACTUAL BEHAVIOR :
No exception is expected in this case

###@###.### 2005-06-16 09:03:33 GMT
See below for the test case. Access was requested by java.net users who are active on the dev forum.

% cat tabbedpanebug.java
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.*;

/**
 * @author ###@###.###
 */
public class TabbedPaneBug extends JFrame implements ChangeListener{
        JTabbedPane tbp = new JTabbedPane();

        public static void main(String[] args) {
                new TabbedPaneBug();
        }
        
        public TabbedPaneBug(){
                super("JTabbedPane Testing");
                
                tbp.addTab("Tab 1 " , new JLabel("I am JLabel 1"));
                tbp.addTab("Tab 2 " , new JLabel("I am JLabel 2" ));
                tbp.addTab("Tab 3 " , new JLabel("I am JLabel 3 "));
                tbp.addTab("Tab 4 " , new JLabel("I am JLabel 4"));
                
                setLayout(new BorderLayout());
                add(tbp,BorderLayout.CENTER);
                tbp.addChangeListener(this);

                setSize(600,200);
                setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                setVisible(true);
        }

        public void stateChanged(ChangeEvent arg0) {
            tbp.updateUI();
        }
}