import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.layout.VBox;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.scene.control.TreeView;
import javafx.scene.control.TreeItem;
import javafx.scene.control.Button;
import java.util.Arrays;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;

/**
 * An implementation of the TreeView control displaying an expandable tree root
 * node.
 *
 * @see javafx.scene.control.TreeView
 */
public class TreeViewSample1 extends Application {

    final TreeView treeView = new TreeView();

    private void init(Stage primaryStage) {
        VBox root = new VBox();
        primaryStage.setScene(new Scene(root));

        TreeItem<String> treeRoot = new TreeItem<String>("Root node");
        treeRoot.getChildren().addAll(Arrays.asList(
                new TreeItem<String>("Child Node 1"),
                new TreeItem<String>("Child Node 2"),
                new TreeItem<String>("Child Node 3")));

        treeRoot.getChildren().get(2).getChildren().addAll(Arrays.asList(
                new TreeItem<String>("Child Node 4"),
                new TreeItem<String>("Child Node 5"),
                new TreeItem<String>("Child Node 6")));

        treeView.setRoot(treeRoot);
        treeRoot.setExpanded(true);
        Button reset = new Button("Reset");
        reset.setOnAction(new EventHandler<ActionEvent>() {
            public void handle(ActionEvent t) {
                reset();
            }
        });
        root.getChildren().addAll(treeView, reset);
    }

    protected void reset() {
        TreeItem<String> item = new TreeItem<String>("Root node");
        item.getChildren().addAll(Arrays.asList(
                new TreeItem<String>("Child Node 11"),
                new TreeItem<String>("Child Node 12"),
                new TreeItem<String>("Child Node 13")));

        item.getChildren().get(2).getChildren().addAll(Arrays.asList(
                new TreeItem<String>("Child Node 14"),
                new TreeItem<String>("Child Node 15"),
                new TreeItem<String>("Child Node 16")));

        item.setExpanded(true);
        treeView.setRoot(item);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        init(primaryStage);
        primaryStage.show();
    }

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