MetalToolBarUI.createContainerListener() could not be used

Name: nkR10003 Date: 07/04/2001



JavaDoc comments for contListener field and createContainerListener method state:
"protected ContainerListener contListener

      This protected field is implemenation specific. Do not access directly or
      override. Use the create method instead.

      See Also:
            createContainerListener()

protected ContainerListener createContainerListener()

      Creates a container listener that will be added to the JToolBar. If this
      method returns null then it will not be added to the toolbar.
      
      Returns:
            an instance of a ContainerListener or null
"

So one can use createContainerListener() to return an instance of
MetalToolBarUI.MetalContainerListener to support super class
functionality and supply additional behavior. In this case component
removal fails with NPE.

Example below demonstrates this problem:
------------------example--------------------
import javax.swing.plaf.metal.*;
import javax.swing.*;
import java.awt.event.*;
class StubToolBarUI extends MetalToolBarUI {
    StubToolBarUI() {
        super();
    }
    
    protected ContainerListener createContainerListener() {
        return new StubContainerListener();
    }
    
    class StubContainerListener extends MetalToolBarUI.MetalContainerListener {
        public void componentAdded(ContainerEvent e) {
            super.componentAdded(e);
            System.out.println("Component Added");
        }
        
        public void componentRemoved(ContainerEvent e) {
            super.componentRemoved(e);
            System.out.println("Component Removed");
        }
    }
}
public class jdk_bug31_test {
    public static void main(String[] args) {
         JToolBar toolBar = new JToolBar();
         StubToolBarUI ui = new StubToolBarUI();
         toolBar.setUI(ui);
         JButton button = new JButton("test");
         try {
            toolBar.add(button);
            toolBar.remove(button);
         } catch(Exception e) {
             System.out.println("Test Failed");
             e.printStackTrace();
             System.exit(-1);
         }
         
         System.out.println("Test Passed");
         System.exit(0);
    }
}
----------------output-----------------------
Component Added
Test Failed
java.lang.NullPointerException
at javax.swing.plaf.basic.BasicToolBarUI.setBorderToNormal(BasicToolBarUI.java:647)
at javax.swing.plaf.basic.BasicToolBarUI$ToolBarContListener.componentRemoved(BasicToolBarUI.java:1016)
at StubToolBarUI$StubContainerListener.componentRemoved(jdk_bug31_test.java:20)
at java.awt.AWTEventMulticaster.componentRemoved(AWTEventMulticaster.java:151)
at java.awt.Container.processContainerEvent(Container.java:1358)
at java.awt.Container.processEvent(Container.java:1334)
at java.awt.Component.dispatchEventImpl(Component.java:3476)
at java.awt.Container.dispatchEventImpl(Container.java:1399)
at java.awt.Component.dispatchEvent(Component.java:3343)
at java.awt.Container.remove(Container.java:564)
at java.awt.Container.remove(Container.java:589)
at jdk_bug31_test.main(jdk_bug31_test.java:33)
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