TreeView(TreeItem < T > root) constructor from TreeView has the following syntax.
public TreeView(TreeItem < T > root)
In the following code shows how to use TreeView.TreeView(TreeItem < T > root) constructor.
/*from w ww. j a v a 2 s .c om*/ import javafx.application.Application; import javafx.scene.Group; import javafx.scene.Scene; import javafx.scene.control.TreeItem; import javafx.scene.control.TreeView; import javafx.scene.layout.VBox; import javafx.stage.Stage; public class Main extends Application { public static void main(String[] args) { launch(args); } @Override public void start(Stage stage) { Scene scene = new Scene(new Group()); stage.setTitle("Button Sample"); stage.setWidth(300); stage.setHeight(190); VBox vbox = new VBox(); vbox.setLayoutX(20); vbox.setLayoutY(20); TreeItem<String> root = new TreeItem<String>("Root Node"); root.setExpanded(true); root.getChildren().addAll( new TreeItem<String>("Item 1"), new TreeItem<String>("Item 2"), new TreeItem<String>("Item 3") ); TreeView<String> treeView = new TreeView<String>(root); vbox.getChildren().add(treeView); vbox.setSpacing(10); ((Group) scene.getRoot()).getChildren().add(vbox); stage.setScene(scene); stage.show(); } }