Using ComboBox as an editor for treenodes

Question

I have a customized combobox editor for editing treenodes. The treenodes may or may not editable based on a particular condition in the userobject at each node.
The node and the combobox are rendered fine but as soon as I select an item from the combobox, i see the following error messages in the stack trace and the code goes into an infinite loop :
Exception occurred during event dispatching:
java.lang.StackOverflowError
     at java.lang.ref.Reference.<init>(Reference.java:198)
     at java.lang.ref.FinalReference.<init>(FinalReference.java:19)
     at java.lang.ref.Finalizer.<init>(Finalizer.java:69)
     at java.lang.ref.Finalizer.register(Finalizer.java:75)
     at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:883)
     at javax.swing.JComboBox.contentsChanged(JComboBox.java:950)
     at javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:79)
     at javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:86)

Answer 1

Here's the code for the custom combobox editor:
public class ScmComboBoxEditor extends DefaultCellEditor
private JTree m_tree;
/* private JComboBox m_comboBox;
protected EventListenerList _treeNodeListeners = new EventListenerList();
protected ChangeEvent changeEvent = null;
public ScmComboBoxEditor(JTree tree, JComboBox combo)
super(combo);
m_tree = tree;
setClickCountToStart(3);
public Component getTreeCellEditorComponent(JTree tree, Object value,
                              boolean isSelected,
                              boolean expanded,
                              boolean leaf, int row)
Component comp = super.getTreeCellEditorComponent(tree, value, isSelected, expanded, leaf, row);
if(comp instanceof JComboBox)
JComboBox combo = (JComboBox)comp;
ScmTreeNode thisNode = (ScmTreeNode)value;
/* if(thisNode.getUserObject() instanceof ScmObject)
ScmObject thisObj = (ScmObject)thisNode.getUserObject();
Vector vItems = new Vector();
vItems.addElement(thisObj);
for(int j = 0; j < 3; j++)
ScmObject obj = new ScmObject();
obj.setName("Branch" + (j+1));
vItems.addElement(obj);
DefaultComboBoxModel comboModel = new DefaultComboBoxModel(vItems);
combo.setModel(comboModel);
if(thisNode.getUserObject() instanceof MappableProject)
MappableProject thisObj = (MappableProject)thisNode.getUserObject();
if(thisObj.hasBranches())
Vector vItems = new Vector();
vItems.addElement(thisObj);
for(int j = 0; j < 3; j++)
MappableProject obj = new MappableProject();
obj.setName("Branch" + (j+1));
vItems.addElement(obj);
DefaultComboBoxModel comboModel = new DefaultComboBoxModel(vItems);
combo.setModel(comboModel);
else if(thisNode.getUserObject() instanceof MappableFolder)
MappableFolder thisObj = (MappableFolder)thisNode.getUserObject();
if(thisObj.hasBranches())
Vector vItems = new Vector();
vItems.addElement(thisObj);
for(int j = 0; j < 3; j++)
MappableProject obj = new MappableProject();
obj.setName("Branch" + (j+1));
vItems.addElement(obj);
DefaultComboBoxModel comboModel = new DefaultComboBoxModel(vItems);
combo.setModel(comboModel);
return comp;
public boolean isCellEditable(EventObject ev)
boolean rv = false;
if(ev instanceof MouseEvent)
MouseEvent me = (MouseEvent)ev;
System.out.println("Clicks = " + me.getClickCount());
if(me.getClickCount() == this.getClickCountToStart())
TreePath path = m_tree.getPathForLocation(me.getX(), me.getY());
ScmTreeNode node = (ScmTreeNode)path.getLastPathComponent();
if(((ScmObject)node.getUserObject()).hasBranches())
rv = true;
return rv;
public boolean stopCellEditing()
this.fireEditingStopped();
return false;
public void cancelCellEditing()
this.fireEditingCanceled();
/* public void addCellEditorListener(CellEditorListener l)
_treeNodeListeners.add(CellEditorListener.class, l);
public void removeCellEditorListener(CellEditorListener l)
_treeNodeListeners.remove(CellEditorListener.class, l);
protected void fireEditingStopped()
Object[] listeners = _treeNodeListeners.getListenerList();
for(int i = listeners.length-2; i >= 0; i-=2)
if(changeEvent == null)
changeEvent = new ChangeEvent(this);
((CellEditorListener)listeners[i+1]).editingStopped(changeEvent);
protected void fireEditingCanceled()
Object[] listeners = _treeNodeListeners.getListenerList();
for(int i = listeners.length-2; i >= 0; i-=2)
if(changeEvent == null)
changeEvent = new ChangeEvent(this);
((CellEditorListener)listeners[i+1]).editingCanceled(changeEvent);
public void setCellEditorValue(Object value)
m_comboBox = (JComboBox)this.editorComponent;
m_comboBox.setSelectedItem(value);
}