JavaFX TreeView hide context menu when tree is empty - javafx

Question

I have a TreeView with a context menu, all works except when tree is empty. When tree is empty, I want to prevent show context menu to user.
//Set up context menu and menu items
final ContextMenu contextMenu = new ContextMenu();
final MenuItem miSubir = new MenuItem("Subir");
final MenuItem miBajar = new MenuItem("Bajar");
final MenuItem miBorrar = new MenuItem("Borrar");
//add events from clic on menu items
miBorrar.setOnAction((ActionEvent event) -> {
...
});
...
//Add menu items to context menu
contextMenu.getItems().add(miSubir);
contextMenu.getItems().add(miBajar);
contextMenu.getItems().add(miBorrar);
//Associate context menu to treeview
treeEjercicios.setContextMenu(contextMenu);
When I use Table component, I fix the problem with:
row.contextMenuProperty().bind(
Bindings.when(row.emptyProperty())
.then((ContextMenu) null)
.otherwise(contextMenu)
);
But I don't know how to apply to use with TreeView or any other alternative?

Answer 1

If the root item is shown, i.e. tree.setShowRoot(true), it can be supposed that when the root item is null the treeview is empty. So we can bind it
tree.contextMenuProperty().bind(
Bindings.when( Bindings.isNull( tree.rootProperty() ) )
.then( (ContextMenu) null)
.otherwise( contextMenu )
);
Else if the root item is not show, then the tree can be supposed to be empty if this root item has no children, i.e. when isLeaf() returns true. In this case the binding will be:
tree.contextMenuProperty().bind(
Bindings.when( tree.getRoot().leafProperty() )
.then( ( ContextMenu ) null )
.otherwise( contextMenu )
);