How to make certain JavaFX TreeView nodes non-selectable?

Question

I would like to make the 'folder' nodes in my JavaFX TreeView expandable and collapsible but not selectable.

I found this discussion and looked into EventFilter, but there does not appear to be any EventType that corresponds with TreeView selection changes. The second suggestion, a custom selection model, sounds like a deep dive to me. So, am I stuck allowing the selection events to trigger my listener and then sort through the trash there?

Answer 1

It's a bit hacky, but I ended up doing it like this:

table.getSelectionModel().selectedItemProperty().addListener((observable, oldValue, newValue) -> {
    if (newValue != null && !newValue.isLeaf()) {
        Platform.runLater(() -> table.getSelectionModel().clearSelection());
    }
});

For me it was enough to just clear the selection when clicking a non-leaf node. However, it shouldn't be to hard to just reselect the oldValue parameter, but be aware that this will fire a change event again (so does the clearSelection call, that's why the newValue != null check is necessary).

Answer 2

There is a similar question posted here:

TreeView - Certain TreeItems are not allowed to be selected

If you use the FilteredTreeViewSelectionModel in the answer that I posted there you can get the desired behaviour by creating a custom TreeItemSelectionFilter and wiring everything up as follows:

MultipleSelectionModel<TreeItem<Object>> selectionModel = tree.getSelectionModel();
TreeItemSelectionFilter<Object> filter = TreeItem::isLeaf;
FilteredTreeViewSelectionModel<Object> filteredSelectionModel = new 
FilteredTreeViewSelectionModel<>(tree, selectionModel, filter);
tree.setSelectionModel(filteredSelectionModel);

This will ensure that only leaf-nodes can be selected as you require.

Answer 3

You can override updateItem method in a TreeCell object . This is a single class app . So, you can test it . Be careful , this aproach would be work with leaf nodes only , because disabled parent nodes can't expand or collapse .

package com.app;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TreeCell;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class App extends Application {

@Override
public void start(Stage stage) {

    TreeView<String> treeView = new TreeView<>();
    treeView.setRoot(new TreeItem<>("People"));
    treeView.getRoot().getChildren().addAll(
            new TreeItem<>("Fernanado"),
            new TreeItem<>("María"),
            new TreeItem<>("Flor"),
            new TreeItem<>("Pablo"),
            new TreeItem<>("Francisca"));

    treeView.setCellFactory(p -> new TreeCell<String>() {
        @Override
        public void updateItem(String string, boolean empty) {
            super.updateItem(string, empty);
            if (empty) {
                setText("");
                setGraphic(null);
            } else {
                setText(string);
                setGraphic(getTreeItem().getGraphic());
   // this will disable a TreeItem if String has "F" character            
                setDisable(string.contains("F"));

            }
        }
    });

    Scene scene = new Scene(new StackPane(treeView), 640, 480);
    stage.setScene(scene);
    stage.show();
}

public static void main(String[] args) {
    launch();
}

}