JTree node as non editable

[Suganthi Velliah]

Hi,

Does anyone have idea on how to make some specific nodes in JTree as non editable.

My tree structure is as follows:

Root 1
|
Parent 1
|
Child 1
......
Child n
.....
|
Parent n

Root 2
Root 3
......
Root n

where I want the nodes Root 1, Root2....Root n to be non editable.
But the Parent nodes and child nodes to be editable.
The tree has popup which has options for renaming these nodes.
So I have set as follows

tree.setEditable(true);

How to make nodes Root 1, Root2....Root n to be non editable?

[Rob Spoor]

Use a custom TreeCellEditor and implement its isCellEditable method:

class NonRootEditor extends DefaultTreeCellEditor
{
    @Override
    public boolean isCellEditable(EventObject event)
    {
        if (!super.isCellEditable(event))
        {
            return false;
        }
        if (event != null && event.getSource() instanceof JTree && event instanceof MouseEvent)
        {
            MouseEvent mouseEvent = (MouseEvent)event;
            JTree tree = (JTree)event.getSource();
            TreePath path = tree.getPathForLocation(mouseEvent.getX(), mouseEvent.getY());
            return path.getPathCount() > 2; // root and direct children are not editable
        }
        return false;
    }
}

Alternatively, you can return a different editor component:

class NonRootEditor extends DefaultTreeCellEditor
{
    private final DefaultTreeCellRenderer renderer;

    public NonRootEditor(JTree tree, DefaultTreeCellRenderer renderer)
    {
        super(tree, renderer);
        this.renderer = renderer;
    }

    @Override
    public Component getTreeCellEditorComponent(JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row)
    {
        TreePath path = tree.getPathForRow(row);
        if (path.getPathCount() > 2)
        {
            return super.getTreeCellEditorComponent(tree, value, isSelected, expanded, leaf, row);
        }
        return renderer.getTreeCellRendererComponent(tree, value, isSelected, expanded, leaf, row, true); // hasFocus == true
    }
}

This will return a JLabel for editing the root and its direct children instead of a JTextField.

Disclaimer: I haven't tested either solution.

[Suganthi Velliah]

Thanks Rob.
It reallly helped me a lot.

I have another doubt.

When I click on the Parent and child nodes I am able to edit the node with MyTextField. I want Parent nodes to be of legth 15 where as the child nodes to be of length 20. How can I achieve this?

With the following code, I am getting both Parent and Child nodes to be of size 20. But I want different sizes. Please help me out!!!

tree.setEditable(true);
         
         DefaultTreeCellRenderer renderer = (DefaultTreeCellRenderer) tree
         .getCellRenderer();
         
         renderer.setClosedIcon(null);
         renderer.setOpenIcon(null);
         renderer.setLeafIcon(null);
         
         tree.setCellRenderer(renderer);

         //Customized TextField for stopping keystrokes when it reaches  its maximum length
         MyTextField textField = new MyTextField(20); 
         textField.setAutoTab(false);

         TreeCellEditor editor = new DefaultCellEditor(textField);
         TreeCellEditor editor1 = new NonRootEditor(tree,renderer,editor);
         tree.setCellEditor(editor1);

[Rob Spoor]

Again, override getTreeCellEditorComponent. Get the result of super.getTreeCellEditorComponent, cast it to JTextField and set the columns.

[Suganthi Velliah]

I have done as follows. But I am getting ClassCastException in the return statement.Even I tried with JTextField also. I am getting the same exception
In the NonRootEditor class I have written as follows:

public Component getTreeCellEditorComponent(JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row)   
    {   
        TreePath path = tree.getPathForRow(row);   
        if (path.getPathCount() == 3)   
        {   
        	MyTextField node= (MyTextField) super.getTreeCellEditorComponent(tree, value, isSelected, expanded, leaf, row);
        	 node.setMaxLength(14);
        	 node.setAutoTab(false);
        	 return node;
        } else if(path.getPathCount() == 4){
        	 MyTextField node =  (MyTextField) super.getTreeCellEditorComponent(tree, value, isSelected, expanded, leaf, row);
        	 node.setMaxLength(20);
        	 node.setAutoTab(false);
        	 return node;
        }
        return renderer.getTreeCellRendererComponent(tree, value, isSelected, expanded, leaf, row, true); // hasFocus == true
        
    }   

[Suganthi Velliah]

Please tell me where the flaw is?

[Rob Spoor]

Suganthi Velliah wrote:Please tell me where the flaw is?

Apparently, DefaultTreeCellRenderer does not directly return the text field but wraps it in a Container subclass. DefaultCellEditor does not have this problem, so you should be able to use that one instead.