JavaFX. TreeView. Данные при нажатие на Элементы

import java.util.ArrayList;
import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.VBox;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView.EditEvent;
import javafx.scene.control.cell.TextFieldTreeCell;
import javafx.scene.control.TreeView;
import javafx.event.EventHandler;
public class FxTreeViewExample3 extends Application
{
    // Create the TextArea
    private final TextArea textArea = new TextArea();
    public static void main(String[] args) 
    {
        Application.launch(args);
    }
    @Override
    public void start(Stage stage) 
    {
        // Create the TreeViewHelper
        TreeViewHelper helper = new TreeViewHelper();
        // Get the Products
        ArrayList<TreeItem> products = helper.getProducts();
        // Create the TreeView
        TreeView treeView = new TreeView();
        // Create the Root TreeItem
        TreeItem rootItem = new TreeItem("Vehicles");
        // Add children to the root
        rootItem.getChildren().addAll(products);
        // Set the Root Node
        treeView.setRoot(rootItem);     
        // Make the TreeView editable
        treeView.setEditable(true);
        // Set a cell factory to use TextFieldTreeCell
        treeView.setCellFactory(TextFieldTreeCell.forTreeView());
        // Set editing related event handlers (OnEditStart)
        treeView.setOnEditStart(new EventHandler<TreeView.EditEvent>()
        {
            @Override
            public void handle(EditEvent event) 
            {
                editStart(event);
            }
        });
        // Set editing related event handlers (OnEditCommit)
        treeView.setOnEditCommit(new EventHandler<TreeView.EditEvent>()
        {
            @Override
            public void handle(EditEvent event) 
            {
                editCommit(event);
            }
        });
        // Set editing related event handlers (OnEditCancel)
        treeView.setOnEditCancel(new EventHandler<TreeView.EditEvent>()
        {
            @Override
            public void handle(EditEvent event) 
            {
                editCancel(event);
            }
        });
        // Set the preferred number of text rows
        textArea.setPrefRowCount(15);
        // Set the preferred number of text columns
        textArea.setPrefColumnCount(25);
        // Create the VBox
        VBox root = new VBox();
        // Add the TreeView to the VBox
        root.getChildren().addAll(treeView,new Label("Message Log:"), textArea);
        // Create the Scene
        Scene scene = new Scene(root,400,500);
        // Add the Scene to the Stage
        stage.setScene(scene);
        // Set the Title for the Scene
        stage.setTitle("TreeView Example 3");
        // Display the stage
        stage.show();
    }
    // Helper Methods for the Event Handlers
    private void editStart(TreeView.EditEvent event) 
    {
        writeMessage("Started editing: " + event.getTreeItem() );
    }
    private void editCommit(TreeView.EditEvent event) 
    {
        writeMessage(event.getTreeItem() + " changed." +
                " old = " + event.getOldValue() +
                ", new = " + event.getNewValue());
    }
    private void editCancel(TreeView.EditEvent e) 
    {
        writeMessage("Cancelled editing: " + e.getTreeItem() );
    }
    // Method for Logging
    private void writeMessage(String msg)
    {
        this.textArea.appendText(msg + "\n");
    }
}

Подробнее пример описан здесь : https://examples.javacodegeeks.com/core-java/javafx-treeview-example/