JavaFX Tree View Height According to Content - treeview

Question

I have number of treeviews in VBox.
I want treeview to take a height based on the number of nodes visible.
Say if I collapse root node of treeview then height of that treeview should also change.
In the case of this image Item0 shows 7 subitems and then there is a lot of whitespace and then Item1 starts, Item1 is collapsed now , so Item2 should start immediately below Item1.
Please tell me what is the right way of doing this.

Answer 1

Try this
#Override
public void start(Stage primaryStage) {
VBox treeContainer = new VBox();
TreeItem<String> hiddenRootItem = new TreeItem<String>();
TreeView<String> tree = new TreeView<String>(hiddenRootItem);
tree.setShowRoot(false);
treeContainer.getChildren().add(tree);
for (int j = 0; j < 3; ++j) {
TreeItem<String> rootItem = new TreeItem<String>("Item " + j);
rootItem.setExpanded(true);
String[] names = {"SubItem1", "SubItem2", "SubItem3", "SubItem4", "SubItem5", "SubItem6", "SubItem7",};
for (int i = 0; i < names.length; i++) {
TreeItem<String> item = new TreeItem<String>(names[i]);
rootItem.getChildren().add(item);
}
hiddenRootItem.getChildren().add(rootItem);
}
StackPane root = new StackPane();
root.getChildren().add(treeContainer);
Scene scene = new Scene(root, 300, 250);
primaryStage.setScene(scene);
primaryStage.show();
}