Module javafx.controls
Package javafx.scene.control

# Class TreeTableView<S>

java.lang.Object
javafx.scene.Node
javafx.scene.Parent
javafx.scene.layout.Region
javafx.scene.control.Control
javafx.scene.control.TreeTableView<S>

Type Parameters:
  `S` - The type of the TreeItem instances used in this TreeTableView.

All Implemented Interfaces:
  `Styleable`, `EventTarget`, `Skinnable`

    @DefaultProperty("root")
    public class TreeTableView<S>
    extends Control

The TreeTableView control is designed to visualize an unlimited number of rows of data, broken out into columns. The TreeTableView control is conceptually very similar to the `TreeView` and `TableView` controls, and as you read on you'll come to see the APIs are largely the same. However, to give a high-level overview, you'll note that the TreeTableView uses the same `TreeItem` API as `TreeView`, and that you therefore are required to simply set the `root node` in the TreeTableView. Similarly, the TreeTableView control makes use of the same TableColumn-based approach that the `TableView` control uses, except instead of using the TableView-specific `TableColumn` class, you should instead use the TreeTableView-specific `TreeTableColumn` class instead. For an example on how to create a TreeTableView instance, refer to the 'Creating a TreeTableView' control section below.

As with the `TableView` control, the TreeTableView control has a number of features, including:

- Powerful `TreeTableColumn` API:
  - Support for `cell factories` to easily customize `cell` contents in both rendering and editing states.
  - Specification of `minWidth`/ `prefWidth`/ `maxWidth`, and also `fixed width columns`.
  - Width resizing by the user at runtime.
  - Column reordering by the user at runtime.
  - Built-in support for `column nesting`
- Different `resizing policies` to dictate what happens when the user resizes columns.
- Support for `multiple column sorting` by clicking the column header (hold down Shift keyboard key whilst clicking on a header to sort by multiple columns).

## Creating a TreeTableView

Creating a TreeTableView is a multi-step process, and also depends on the underlying data model needing to be represented. For this example we'll use the TreeTableView to visualise a file system, and will therefore make use of an imaginary (and vastly simplified) File class as defined below:

     public class File {
         private StringProperty name;
         public void setName(String value) { nameProperty().set(value); }
         public String getName() { return nameProperty().get(); }
         public StringProperty nameProperty() {
             if (name == null) name = new SimpleStringProperty(this, "name");
             return name;
         }

         private LongProperty lastModified;
         public void setLastModified(long value) { lastModifiedProperty().set(value); }
         public long getLastModified() { return lastModifiedProperty().get(); }
         public LongProperty lastModifiedProperty() {
             if (lastModified == null) lastModified = new SimpleLongProperty(this, "lastModified");
             return lastModified;
         }

         public File(String name, long size) {
             setName(name);
             setSize(size);
         }
     }

The data we will use for this example is a single root with 3 files:

     File rootFile = new File("Images", 900);
     List<File> files = List.of(
         new File("Cat.png", 300),
         new File("Dog.png", 500),
         new File("Bird.png", 100));

Firstly, we need to create a data model. As mentioned, for this example, we'll be representing a file system using File instances. To do this, we need to define the root node of the tree table and its hierarchy:

     TreeItem<File> root = new TreeItem<>(rootFile);
     files.forEach(file -> root.getChildren().add(new TreeItem<>(file)));

Then we create a TreeTableView instance:

     TreeTableView<File> treeTable = new TreeTableView<>(root);

With the root set as such, the TreeTableView will automatically update whenever the `children` of the root change.

At this point we have a TreeTableView hooked up to observe the root TreeItem instance. The missing ingredient now is the means of splitting out the data contained within the model and representing it in one or more `TreeTableColumn` instances. To create a two-column TreeTableView to show the file name and size properties, we write:

     TreeTableColumns<File, String> fileNameCol = new TreeTableColumn<>("Filename");
     TreeTableColumns<File, Long> sizeCol = new TreeTableColumn<>("Size");

     treeTable.getColumns().setAll(fileNameCol, sizeCol);

With the code shown above we have nearly fully defined the minimum properties required to create a TreeTableView instance. The only thing missing is the `cell value factories` for the two columns - it is these that are responsible for determining the value of a cell in a given row. Commonly these can be specified using the `TreeItemPropertyValueFactory` class, but failing that you can also create an anonymous inner class and do whatever is necessary. For example, using `TreeItemPropertyValueFactory` you would do the following:

     fileNameCol.setCellValueFactory(new TreeItemPropertyValueFactory(rootFile.nameProperty().getName()));
     sizeCol.setCellValueFactory(new TreeItemPropertyValueFactory(rootFile.sizeProperty().getName()));

Running this code will result in a TreeTableView as shown above with two columns for name and size. Any other properties the File class might have will not be shown, as no TreeTableColumns are defined for them.

### TreeTableView support for classes that don't contain properties

The code shown above is the shortest possible code for creating a TreeTableView when the domain objects are designed with JavaFX properties in mind (additionally, `TreeItemPropertyValueFactory` supports normal JavaBean properties too, although there is a caveat to this, so refer to the class documentation for more information). When this is not the case, it is necessary to provide a custom cell value factory. More information about cell value factories can be found in the `TreeTableColumn` API documentation, but briefly, here is how a TreeTableColumns could be specified:

     firstNameCol.setCellValueFactory(new Callback<CellDataFeatures<Person, String>, ObservableValue<String>>() {
         public ObservableValue<String> call(CellDataFeatures<Person, String> p) {
             // p.getValue() returns the TreeItem<Person> instance for a particular TreeTableView row,
             // p.getValue().getValue() returns the Person instance inside the TreeItem<Person>
             return p.getValue().getValue().firstNameProperty();
         }
     });

     // or with a lambda expression:
     firstNameCol.setCellValueFactory(p -> p.getValue().getValue().firstNameProperty());

### TreeTableView Selection / Focus APIs

To track selection and focus, it is necessary to become familiar with the `SelectionModel` and `FocusModel` classes. A TreeTableView has at most one instance of each of these classes, available from `selectionModel` and `focusModel` properties, respectively. Whilst it is possible to use this API to set a new selection model, in most circumstances this is not necessary - the default selection and focus models should work in most circumstances.

The default `SelectionModel` used when instantiating a TreeTableView is an implementation of the `MultipleSelectionModel` abstract class. However, as noted in the API documentation for the `selectionMode` property, the default value is `SelectionMode.SINGLE`. To enable multiple selection in a default TreeTableView instance, it is therefore necessary to do the following:

     treeTableView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);

### Customizing TreeTableView Visuals

The visuals of the TreeTableView can be entirely customized by replacing the default `row factory`. A row factory is used to generate `TreeTableRow` instances, which are used to represent an entire row in the TreeTableView.

In many cases, this is not what is desired however, as it is more commonly the case that cells be customized on a per-column basis, not a per-row basis. It is therefore important to note that a `TreeTableRow` is not a `TreeTableCell`. A `TreeTableRow` is simply a container for zero or more `TreeTableCell`, and in most circumstances it is more likely that you'll want to create custom TreeTableCells, rather than TreeTableRows. The primary use case for creating custom TreeTableRow instances would most probably be to introduce some form of column spanning support.

You can create custom `TreeTableCell` instances per column by assigning the appropriate function to the TreeTableColumns `cell factory` property.

See the `Cell` class documentation for a more complete description of how to write custom Cells.

### Editing

This control supports inline editing of values, and this section attempts to give an overview of the available APIs and how you should use them.

Firstly, cell editing most commonly requires a different user interface than when a cell is not being edited. This is the responsibility of the `Cell` implementation being used. For TreeTableView, it is highly recommended that editing be `per-TreeTableColumn`, rather than `per row`, as more often than not you want users to edit each column value differently, and this approach allows for editors specific to each column. It is your choice whether the cell is permanently in an editing state (e.g. this is common for `CheckBox` cells), or to switch to a different UI when editing begins (e.g. when a double-click is received on a cell).

To know when editing has been requested on a cell, simply override the `Cell.startEdit()` method, and update the cell `text` and `graphic` properties as appropriate (e.g. set the text to null and set the graphic to be a `TextField`). Additionally, you should also override `Cell.cancelEdit()` to reset the UI back to its original visual state when the editing concludes. In both cases it is important that you also ensure that you call the super method to have the cell perform all duties it must do to enter or exit its editing mode.

Once your cell is in an editing state, the next thing you are most probably interested in is how to commit or cancel the editing that is taking place. This is your responsibility as the cell factory provider. Your cell implementation will know when the editing is over, based on the user input (e.g. when the user presses the Enter or ESC keys on their keyboard). When this happens, it is your responsibility to call `Cell.commitEdit(Object)` or `Cell.cancelEdit()`, as appropriate.

When you call `Cell.commitEdit(Object)` an event is fired to the TreeTableView, which you can observe by adding an `EventHandler` via `TreeTableColumn.setOnEditCommit(javafx.event.EventHandler)`. Similarly, you can also observe edit events for `edit start` and `edit cancel`.

By default the TreeTableColumn edit commit handler is non-null, with a default handler that attempts to overwrite the property value for the item in the currently-being-edited row. It is able to do this as the `Cell.commitEdit(Object)` method is passed in the new value, and this is passed along to the edit commit handler via the `CellEditEvent` that is fired. It is simply a matter of calling `TreeTableColumn.CellEditEvent.getNewValue()` to retrieve this value.

It is very important to note that if you call `TreeTableColumn.setOnEditCommit(javafx.event.EventHandler)` with your own `EventHandler`, then you will be removing the default handler. Unless you then handle the writeback to the property (or the relevant data source), nothing will happen. You can work around this by using the `TableColumnBase.addEventHandler(javafx.event.EventType, javafx.event.EventHandler)` method to add a `TreeTableColumn.EDIT_COMMIT_EVENT` `EventType` with your desired `EventHandler` as the second argument. Using this method, you will not replace the default implementation, but you will be notified when an edit commit has occurred.

Hopefully this summary answers some of the commonly asked questions. Fortunately, JavaFX ships with a number of pre-built cell factories that handle all the editing requirements on your behalf. You can find these pre-built cell factories in the javafx.scene.control.cell package.

Since:
  JavaFX 8.0
See Also:
  `TreeTableColumn`, `TreeTablePosition`

- ## Property Summary

  Properties
  Type | Property | Description
  --- | --- | ---
  `ObjectProperty<Callback<TreeTableView.ResizeFeatures,​Boolean>>` | `columnResizePolicy` | This is the function called when the user completes a column-resize operation.
  `ReadOnlyObjectProperty<Comparator<TreeItem<S>>>` | `comparator` | The comparator property is a read-only property that is representative of the current state of the `sort order` list.
  `BooleanProperty` | `editable` | Specifies whether this TreeTableView is editable - only if the TreeTableView and the TreeCells within it are both editable will a TreeCell be able to go into their editing state.
  `ReadOnlyObjectProperty<TreeTablePosition<S,​?>>` | `editingCell` | Represents the current cell being edited, or null if there is no cell being edited.
  `ReadOnlyIntegerProperty` | `expandedItemCount` | Represents the number of tree nodes presently able to be visible in the TreeTableView.
  `DoubleProperty` | `fixedCellSize` | Specifies whether this control has cells that are a fixed height (of the specified value).
  `ObjectProperty<TreeTableView.TreeTableViewFocusModel<S>>` | `focusModel` | The FocusModel provides the API through which it is possible to control focus on zero or one rows of the TreeTableView.
  `ObjectProperty<EventHandler<ScrollToEvent<TreeTableColumn<S,​?>>>>` | `onScrollToColumn` | Called when there's a request to scroll a column into view using `scrollToColumn(TreeTableColumn)` or `scrollToColumnIndex(int)`
  `ObjectProperty<EventHandler<ScrollToEvent<Integer>>>` | `onScrollTo` | Called when there's a request to scroll an index into view using `scrollTo(int)`
  `ObjectProperty<EventHandler<SortEvent<TreeTableView<S>>>>` | `onSort` | Called when there's a request to sort the control.
  `ObjectProperty<Node>` | `placeholder` | This Node is shown to the user when the table has no content to show.
  `ObjectProperty<TreeItem<S>>` | `root` | Property representing the root node of the TreeTableView.
  `ObjectProperty<Callback<TreeTableView<S>,​TreeTableRow<S>>>` | `rowFactory` | A function which produces a TreeTableRow.
  `ObjectProperty<TreeTableView.TreeTableViewSelectionModel<S>>` | `selectionModel` | The SelectionModel provides the API through which it is possible to select single or multiple items within a TreeTableView, as well as inspect which rows have been selected by the user.
  `BooleanProperty` | `showRoot` | Property that represents whether or not the TreeTableView root node is visible.
  `ObjectProperty<TreeSortMode>` | `sortMode` | Specifies the sort mode to use when sorting the contents of this TreeTableView, should any columns be specified in the `sort order` list.
  `ObjectProperty<Callback<TreeTableView<S>,​Boolean>>` | `sortPolicy` | The sort policy specifies how sorting in this TreeTableView should be performed.
  `BooleanProperty` | `tableMenuButtonVisible` | This controls whether a menu button is available when the user clicks in a designated space within the TableView, within which is a radio menu item for each TreeTableColumn in this table.
  `ObjectProperty<TreeTableColumn<S,​?>>` | `treeColumn` | Property that represents which column should have the disclosure node shown in it (that is, the column with the arrow).

  ### Properties inherited from class javafx.scene.control.Control

  `contextMenu, skin, tooltip`

  ### Properties inherited from class javafx.scene.layout.Region

  `background, border, cacheShape, centerShape, height, insets, maxHeight, maxWidth, minHeight, minWidth, opaqueInsets, padding, prefHeight, prefWidth, scaleShape, shape, snapToPixel, width`

  ### Properties inherited from class javafx.scene.Parent

  `needsLayout`

  ### Properties inherited from class javafx.scene.Node

  `accessibleHelp, accessibleRoleDescription, accessibleRole, accessibleText, blendMode, boundsInLocal, boundsInParent, cacheHint, cache, clip, cursor, depthTest, disabled, disable, effectiveNodeOrientation, effect, eventDispatcher, focused, focusTraversable, hover, id, inputMethodRequests, layoutBounds, layoutX, layoutY, localToParentTransform, localToSceneTransform, managed, mouseTransparent, nodeOrientation, onContextMenuRequested, onDragDetected, onDragDone, onDragDropped, onDragEntered, onDragExited, onDragOver, onInputMethodTextChanged, onKeyPressed, onKeyReleased, onKeyTyped, onMouseClicked, onMouseDragEntered, onMouseDragExited, onMouseDragged, onMouseDragOver, onMouseDragReleased, onMouseEntered, onMouseExited, onMouseMoved, onMousePressed, onMouseReleased, onRotate, onRotationFinished, onRotationStarted, onScrollFinished, onScroll, onScrollStarted, onSwipeDown, onSwipeLeft, onSwipeRight, onSwipeUp, onTouchMoved, onTouchPressed, onTouchReleased, onTouchStationary, onZoomFinished, onZoom, onZoomStarted, opacity, parent, pickOnBounds, pressed, rotate, rotationAxis, scaleX, scaleY, scaleZ, scene, style, translateX, translateY, translateZ, viewOrder, visible`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type | Class | Description
  --- | --- | ---
  `static class` | `TreeTableView.EditEvent<S>` | An `Event` subclass used specifically in TreeTableView for representing edit-related events.
  `static class` | `TreeTableView.ResizeFeatures<S>` | An immutable wrapper class for use in the TableView `column resize` functionality.
  `static class` | `TreeTableView.TreeTableViewFocusModel<S>` | A `FocusModel` with additional functionality to support the requirements of a TableView control.
  `static class` | `TreeTableView.TreeTableViewSelectionModel<S>` | A simple extension of the `SelectionModel` abstract class to allow for special support for TreeTableView controls.

- ## Field Summary

  Fields
  Modifier and Type | Field | Description
  --- | --- | ---
  `static Callback<TreeTableView.ResizeFeatures,​Boolean>` | `CONSTRAINED_RESIZE_POLICY` | Simple policy that ensures the width of all visible leaf columns in this table sum up to equal the width of the table itself.
  `static Callback<TreeTableView,​Boolean>` | `DEFAULT_SORT_POLICY` | The default `sort policy` that this TreeTableView will use if no other policy is specified.
  `static Callback<TreeTableView.ResizeFeatures,​Boolean>` | `UNCONSTRAINED_RESIZE_POLICY` | Very simple resize policy that just resizes the specified column by the provided delta and shifts all other columns (to the right of the given column) further to the right (when the delta is positive) or to the left (when the delta is negative).

  ### Fields inherited from class javafx.scene.layout.Region

  `USE_COMPUTED_SIZE, USE_PREF_SIZE`

  ### Fields inherited from class javafx.scene.Node

  `BASELINE_OFFSET_SAME_AS_HEIGHT`

- ## Constructor Summary

  Constructors
  Constructor | Description
  --- | ---
  `TreeTableView()` | Creates an empty TreeTableView.
  `TreeTableView​(TreeItem<S> root)` | Creates a TreeTableView with the provided root node.

- ## Method Summary

  Modifier and Type | Method | Description
  --- | --- | ---
  `ObjectProperty<Callback<TreeTableView.ResizeFeatures,​Boolean>>` | `columnResizePolicyProperty()` | This is the function called when the user completes a column-resize operation.
  `ReadOnlyObjectProperty<Comparator<TreeItem<S>>>` | `comparatorProperty()` | The comparator property is a read-only property that is representative of the current state of the `sort order` list.
  `protected Skin<?>` | `createDefaultSkin()` | Create a new instance of the default skin for this control.
  `void` | `edit​(int row, TreeTableColumn<S,​?> column)` | Causes the cell at the given row/column view indexes to switch into its editing state, if it is not already in it, and assuming that the TableView and column are also editable.
  `BooleanProperty` | `editableProperty()` | Specifies whether this TreeTableView is editable - only if the TreeTableView and the TreeCells within it are both editable will a TreeCell be able to go into their editing state.
  `static <S> EventType<TreeTableView.EditEvent<S>>` | `editAnyEvent()` | An EventType that indicates some edit event has occurred.
  `static <S> EventType<TreeTableView.EditEvent<S>>` | `editCancelEvent()` | An EventType used to indicate that an edit event has just been canceled within the TreeTableView upon which the event was fired.
  `static <S> EventType<TreeTableView.EditEvent<S>>` | `editCommitEvent()` | An EventType that is used to indicate that an edit in a TreeTableView has been committed.
  `ReadOnlyObjectProperty<TreeTablePosition<S,​?>>` | `editingCellProperty()` | Represents the current cell being edited, or null if there is no cell being edited.
  `static <S> EventType<TreeTableView.EditEvent<S>>` | `editStartEvent()` | An EventType used to indicate that an edit event has started within the TreeTableView upon which the event was fired.
  `ReadOnlyIntegerProperty` | `expandedItemCountProperty()` | Represents the number of tree nodes presently able to be visible in the TreeTableView.
  `DoubleProperty` | `fixedCellSizeProperty()` | Specifies whether this control has cells that are a fixed height (of the specified value).
  `ObjectProperty<TreeTableView.TreeTableViewFocusModel<S>>` | `focusModelProperty()` | The FocusModel provides the API through which it is possible to control focus on zero or one rows of the TreeTableView.
  `static List<CssMetaData<? extends Styleable,​?>>` | `getClassCssMetaData()` |
  `Callback<TreeTableView.ResizeFeatures,​Boolean>` | `getColumnResizePolicy()` | Gets the value of the property columnResizePolicy.
  `ObservableList<TreeTableColumn<S,​?>>` | `getColumns()` | The TreeTableColumns that are part of this TableView.
  `Comparator<TreeItem<S>>` | `getComparator()` | Gets the value of the property comparator.
  `List<CssMetaData<? extends Styleable,​?>>` | `getControlCssMetaData()`
  `TreeTablePosition<S,​?>` | `getEditingCell()` | Gets the value of the property editingCell.
  `int` | `getExpandedItemCount()` | Gets the value of the property expandedItemCount.
  `double` | `getFixedCellSize()` | Returns the fixed cell size value.
  `TreeTableView.TreeTableViewFocusModel<S>` | `getFocusModel()` | Returns the currently installed `FocusModel`.
  `static int` | `getNodeLevel​(TreeItem<?> node)` | Deprecated. This method does not correctly calculate the distance from the given TreeItem to the root of the TreeTableView.
  `EventHandler<ScrollToEvent<Integer>>` | `getOnScrollTo()` | Gets the value of the property onScrollTo.
  `EventHandler<ScrollToEvent<TreeTableColumn<S,​?>>>` | `getOnScrollToColumn()` | Gets the value of the property onScrollToColumn.
  `EventHandler<SortEvent<TreeTableView<S>>>` | `getOnSort()` | Gets the value of the property onSort.
  `Node` | `getPlaceholder()` | Gets the value of the property placeholder.
  `TreeItem<S>` | `getRoot()` | Returns the current root node of this TreeTableView, or null if no root node is specified.
  `int` | `getRow​(TreeItem<S> item)` | Returns the index position of the given TreeItem, assuming that it is currently accessible through the tree hierarchy (most notably, that all parent tree items are expanded).
  `Callback<TreeTableView<S>,​TreeTableRow<S>>` | `getRowFactory()` | Gets the value of the property rowFactory.
  `TreeTableView.TreeTableViewSelectionModel<S>` | `getSelectionModel()` | Returns the currently installed selection model.
  `TreeSortMode` | `getSortMode()` | Gets the value of the property sortMode.
  `ObservableList<TreeTableColumn<S,​?>>` | `getSortOrder()` | The sortOrder list defines the order in which `TreeTableColumn` instances are sorted.
  `Callback<TreeTableView<S>,​Boolean>` | `getSortPolicy()` | Gets the value of the property sortPolicy.
  `TreeTableColumn<S,​?>` | `getTreeColumn()` | Gets the value of the property treeColumn.
  `TreeItem<S>` | `getTreeItem​(int row)` | Returns the TreeItem in the given index, or null if it is out of bounds.
  `int` | `getTreeItemLevel​(TreeItem<?> node)` | Returns the number of levels of 'indentation' of the given TreeItem, based on how many times getParent() can be recursively called.
  `TreeTableColumn<S,​?>` | `getVisibleLeafColumn​(int column)` | Returns the TreeTableColumn in the given column index, relative to all other visible leaf columns.
  `ObservableList<TreeTableColumn<S,​?>>` | `getVisibleLeafColumns()` | Returns an unmodifiable list containing the currently visible leaf columns.
  `int` | `getVisibleLeafIndex​(TreeTableColumn<S,​?> column)` | Returns the position of the given column, relative to all other visible leaf columns.
  `boolean` | `isEditable()` | Gets the value of the property editable.
  `boolean` | `isShowRoot()` | Returns true if the root of the TreeTableView should be shown, and false if it should not.
  `boolean` | `isTableMenuButtonVisible()` | Gets the value of the property tableMenuButtonVisible.
  `protected void` | `layoutChildren()` | Invoked during the layout pass to layout the children in this `Parent`.
  `ObjectProperty<EventHandler<ScrollToEvent<TreeTableColumn<S,​?>>>>` | `onScrollToColumnProperty()` | Called when there's a request to scroll a column into view using `scrollToColumn(TreeTableColumn)` or `scrollToColumnIndex(int)`
  `ObjectProperty<EventHandler<ScrollToEvent<Integer>>>` | `onScrollToProperty()` | Called when there's a request to scroll an index into view using `scrollTo(int)`
  `ObjectProperty<EventHandler<SortEvent<TreeTableView<S>>>>` | `onSortProperty()` | Called when there's a request to sort the control.
  `ObjectProperty<Node>` | `placeholderProperty()` | This Node is shown to the user when the table has no content to show.
  `Object` | `queryAccessibleAttribute​(AccessibleAttribute attribute, Object... parameters)` | This method is called by the assistive technology to request the value for an attribute.
  `void` | `refresh()` | Calling `refresh()` forces the TreeTableView control to recreate and repopulate the cells necessary to populate the visual bounds of the control.
  `boolean` | `resizeColumn​(TreeTableColumn<S,​?> column, double delta)` | Applies the currently installed resize policy against the given column, resizing it based on the delta value provided.
  `ObjectProperty<TreeItem<S>>` | `rootProperty()` | Property representing the root node of the TreeTableView.
  `ObjectProperty<Callback<TreeTableView<S>,​TreeTableRow<S>>>` | `rowFactoryProperty()` | A function which produces a TreeTableRow.
  `void` | `scrollTo​(int index)` | Scrolls the TreeTableView such that the item in the given index is visible to the end user.
  `void` | `scrollToColumn​(TreeTableColumn<S,​?> column)` | Scrolls the TreeTableView so that the given column is visible within the viewport.
  `void` | `scrollToColumnIndex​(int columnIndex)` | Scrolls the TreeTableView so that the given index is visible within the viewport.
  `ObjectProperty<TreeTableView.TreeTableViewSelectionModel<S>>` | `selectionModelProperty()` | The SelectionModel provides the API through which it is possible to select single or multiple items within a TreeTableView, as well as inspect which rows have been selected by the user.
  `void` | `setColumnResizePolicy​(Callback<TreeTableView.ResizeFeatures,​Boolean> callback)` | Sets the value of the property columnResizePolicy.
  `void` | `setEditable​(boolean value)` | Sets the value of the property editable.
  `void` | `setFixedCellSize​(double value)` | Sets the new fixed cell size for this control.
  `void` | `setFocusModel​(TreeTableView.TreeTableViewFocusModel<S> value)` | Sets the `FocusModel` to be used in the TreeTableView.
  `void` | `setOnScrollTo​(EventHandler<ScrollToEvent<Integer>> value)` | Sets the value of the property onScrollTo.
  `void` | `setOnScrollToColumn​(EventHandler<ScrollToEvent<TreeTableColumn<S,​?>>> value)` | Sets the value of the property onScrollToColumn.
  `void` | `setOnSort​(EventHandler<SortEvent<TreeTableView<S>>> value)` | Sets the value of the property onSort.
  `void` | `setPlaceholder​(Node value)` | Sets the value of the property placeholder.
  `void` | `setRoot​(TreeItem<S> value)` | Sets the root node in this TreeTableView.
  `void` | `setRowFactory​(Callback<TreeTableView<S>,​TreeTableRow<S>> value)` | Sets the value of the property rowFactory.
  `void` | `setSelectionModel​(TreeTableView.TreeTableViewSelectionModel<S> value)` | Sets the `MultipleSelectionModel` to be used in the TreeTableView.
  `void` | `setShowRoot​(boolean value)` | Specifies whether the root `TreeItem` should be shown within this TreeTableView.
  `void` | `setSortMode​(TreeSortMode value)` | Sets the value of the property sortMode.
  `void` | `setSortPolicy​(Callback<TreeTableView<S>,​Boolean> callback)` | Sets the value of the property sortPolicy.
  `void` | `setTableMenuButtonVisible​(boolean value)` | Sets the value of the property tableMenuButtonVisible.
  `void` | `setTreeColumn​(TreeTableColumn<S,​?> value)` | Sets the value of the property treeColumn.
  `BooleanProperty` | `showRootProperty()` | Property that represents whether or not the TreeTableView root node is visible.
  `void` | `sort()` | The sort method forces the TreeTableView to re-run its sorting algorithm.
  `ObjectProperty<TreeSortMode>` | `sortModeProperty()` | Specifies the sort mode to use when sorting the contents of this TreeTableView, should any columns be specified in the `sort order` list.
  `ObjectProperty<Callback<TreeTableView<S>,​Boolean>>` | `sortPolicyProperty()` | The sort policy specifies how sorting in this TreeTableView should be performed.
  `BooleanProperty` | `tableMenuButtonVisibleProperty()` | This controls whether a menu button is available when the user clicks in a designated space within the TableView, within which is a radio menu item for each TreeTableColumn in this table.
  `ObjectProperty<TreeTableColumn<S,​?>>` | `treeColumnProperty()` | Property that represents which column should have the disclosure node shown in it (that is, the column with the arrow).

  ### Methods inherited from class javafx.scene.control.Control

  `computeMaxHeight, computeMaxWidth, computeMinHeight, computeMinWidth, computePrefHeight, computePrefWidth, contextMenuProperty, executeAccessibleAction, getBaselineOffset, getContextMenu, getCssMetaData, getInitialFocusTraversable, getSkin, getTooltip, isResizable, setContextMenu, setSkin, setTooltip, skinProperty, tooltipProperty`

  ### Methods inherited from class javafx.scene.layout.Region

  `backgroundProperty, borderProperty, cacheShapeProperty, centerShapeProperty, getBackground, getBorder, getHeight, getInsets, getMaxHeight, getMaxWidth, getMinHeight, getMinWidth, getOpaqueInsets, getPadding, getPrefHeight, getPrefWidth, getShape, getUserAgentStylesheet, getWidth, heightProperty, insetsProperty, isCacheShape, isCenterShape, isScaleShape, isSnapToPixel, layoutInArea, layoutInArea, layoutInArea, layoutInArea, maxHeight, maxHeightProperty, maxWidth, maxWidthProperty, minHeight, minHeightProperty, minWidth, minWidthProperty, opaqueInsetsProperty, paddingProperty, positionInArea, positionInArea, prefHeight, prefHeightProperty, prefWidth, prefWidthProperty, resize, scaleShapeProperty, setBackground, setBorder, setCacheShape, setCenterShape, setHeight, setMaxHeight, setMaxSize, setMaxWidth, setMinHeight, setMinSize, setMinWidth, setOpaqueInsets, setPadding, setPrefHeight, setPrefSize, setPrefWidth, setScaleShape, setShape, setSnapToPixel, setWidth, shapeProperty, snappedBottomInset, snappedLeftInset, snappedRightInset, snappedTopInset, snapPosition, snapPositionX, snapPositionY, snapSize, snapSizeX, snapSizeY, snapSpace, snapSpaceX, snapSpaceY, snapToPixelProperty, widthProperty`

  ### Methods inherited from class javafx.scene.Parent

  `getChildren, getChildrenUnmodifiable, getManagedChildren, getStylesheets, isNeedsLayout, layout, lookup, needsLayoutProperty, requestLayout, requestParentLayout, setNeedsLayout, updateBounds`

  ### Methods inherited from class javafx.scene.Node

  `accessibleHelpProperty, accessibleRoleDescriptionProperty, accessibleRoleProperty, accessibleTextProperty, addEventFilter, addEventHandler, applyCss, autosize, blendModeProperty, boundsInLocalProperty, boundsInParentProperty, buildEventDispatchChain, cacheHintProperty, cacheProperty, clipProperty, computeAreaInScreen, contains, contains, cursorProperty, depthTestProperty, disabledProperty, disableProperty, effectiveNodeOrientationProperty, effectProperty, eventDispatcherProperty, fireEvent, focusedProperty, focusTraversableProperty, getAccessibleHelp, getAccessibleRole, getAccessibleRoleDescription, getAccessibleText, getBlendMode, getBoundsInLocal, getBoundsInParent, getCacheHint, getClip, getContentBias, getCursor, getDepthTest, getEffect, getEffectiveNodeOrientation, getEventDispatcher, getId, getInitialCursor, getInputMethodRequests, getLayoutBounds, getLayoutX, getLayoutY, getLocalToParentTransform, getLocalToSceneTransform, getNodeOrientation, getOnContextMenuRequested, getOnDragDetected, getOnDragDone, getOnDragDropped, getOnDragEntered, getOnDragExited, getOnDragOver, getOnInputMethodTextChanged, getOnKeyPressed, getOnKeyReleased, getOnKeyTyped, getOnMouseClicked, getOnMouseDragEntered, getOnMouseDragExited, getOnMouseDragged, getOnMouseDragOver, getOnMouseDragReleased, getOnMouseEntered, getOnMouseExited, getOnMouseMoved, getOnMousePressed, getOnMouseReleased, getOnRotate, getOnRotationFinished, getOnRotationStarted, getOnScroll, getOnScrollFinished, getOnScrollStarted, getOnSwipeDown, getOnSwipeLeft, getOnSwipeRight, getOnSwipeUp, getOnTouchMoved, getOnTouchPressed, getOnTouchReleased, getOnTouchStationary, getOnZoom, getOnZoomFinished, getOnZoomStarted, getOpacity, getParent, getProperties, getPseudoClassStates, getRotate, getRotationAxis, getScaleX, getScaleY, getScaleZ, getScene, getStyle, getStyleableParent, getStyleClass, getTransforms, getTranslateX, getTranslateY, getTranslateZ, getTypeSelector, getUserData, getViewOrder, hasProperties, hoverProperty, idProperty, inputMethodRequestsProperty, intersects, intersects, isCache, isDisable, isDisabled, isFocused, isFocusTraversable, isHover, isManaged, isMouseTransparent, isPickOnBounds, isPressed, isVisible, layoutBoundsProperty, layoutXProperty, layoutYProperty, localToParent, localToParent, localToParent, localToParent, localToParent, localToParentTransformProperty, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToScene, localToSceneTransformProperty, localToScreen, localToScreen, localToScreen, localToScreen, localToScreen, lookupAll, managedProperty, mouseTransparentProperty, nodeOrientationProperty, notifyAccessibleAttributeChanged, onContextMenuRequestedProperty, onDragDetectedProperty, onDragDoneProperty, onDragDroppedProperty, onDragEnteredProperty, onDragExitedProperty, onDragOverProperty, onInputMethodTextChangedProperty, onKeyPressedProperty, onKeyReleasedProperty, onKeyTypedProperty, onMouseClickedProperty, onMouseDragEnteredProperty, onMouseDragExitedProperty, onMouseDraggedProperty, onMouseDragOverProperty, onMouseDragReleasedProperty, onMouseEnteredProperty, onMouseExitedProperty, onMouseMovedProperty, onMousePressedProperty, onMouseReleasedProperty, onRotateProperty, onRotationFinishedProperty, onRotationStartedProperty, onScrollFinishedProperty, onScrollProperty, onScrollStartedProperty, onSwipeDownProperty, onSwipeLeftProperty, onSwipeRightProperty, onSwipeUpProperty, onTouchMovedProperty, onTouchPressedProperty, onTouchReleasedProperty, onTouchStationaryProperty, onZoomFinishedProperty, onZoomProperty, onZoomStartedProperty, opacityProperty, parentProperty, parentToLocal, parentToLocal, parentToLocal, parentToLocal, parentToLocal, pickOnBoundsProperty, pressedProperty, pseudoClassStateChanged, relocate, removeEventFilter, removeEventHandler, requestFocus, resizeRelocate, rotateProperty, rotationAxisProperty, scaleXProperty, scaleYProperty, scaleZProperty, sceneProperty, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, sceneToLocal, screenToLocal, screenToLocal, screenToLocal, setAccessibleHelp, setAccessibleRole, setAccessibleRoleDescription, setAccessibleText, setBlendMode, setCache, setCacheHint, setClip, setCursor, setDepthTest, setDisable, setDisabled, setEffect, setEventDispatcher, setEventHandler, setFocused, setFocusTraversable, setHover, setId, setInputMethodRequests, setLayoutX, setLayoutY, setManaged, setMouseTransparent, setNodeOrientation, setOnContextMenuRequested, setOnDragDetected, setOnDragDone, setOnDragDropped, setOnDragEntered, setOnDragExited, setOnDragOver, setOnInputMethodTextChanged, setOnKeyPressed, setOnKeyReleased, setOnKeyTyped, setOnMouseClicked, setOnMouseDragEntered, setOnMouseDragExited, setOnMouseDragged, setOnMouseDragOver, setOnMouseDragReleased, setOnMouseEntered, setOnMouseExited, setOnMouseMoved, setOnMousePressed, setOnMouseReleased, setOnRotate, setOnRotationFinished, setOnRotationStarted, setOnScroll, setOnScrollFinished, setOnScrollStarted, setOnSwipeDown, setOnSwipeLeft, setOnSwipeRight, setOnSwipeUp, setOnTouchMoved, setOnTouchPressed, setOnTouchReleased, setOnTouchStationary, setOnZoom, setOnZoomFinished, setOnZoomStarted, setOpacity, setPickOnBounds, setPressed, setRotate, setRotationAxis, setScaleX, setScaleY, setScaleZ, setStyle, setTranslateX, setTranslateY, setTranslateZ, setUserData, setViewOrder, setVisible, snapshot, snapshot, startDragAndDrop, startFullDrag, styleProperty, toBack, toFront, toString, translateXProperty, translateYProperty, translateZProperty, usesMirroring, viewOrderProperty, visibleProperty`

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

  ### Methods inherited from interface javafx.css.Styleable

  `getStyleableNode`

- ## Property Details

  - ### root

    public final ObjectProperty<TreeItem<S>> rootProperty
    Property representing the root node of the TreeTableView.
    Returns:
      the root property

  - ### showRoot

    public final BooleanProperty showRootProperty
    Property that represents whether or not the TreeTableView root node is visible.
    See Also:
      `isShowRoot()`, `setShowRoot(boolean)`

  - ### treeColumn

    public final ObjectProperty<TreeTableColumn<S,​?>> treeColumnProperty
    Property that represents which column should have the disclosure node shown in it (that is, the column with the arrow). By default this will be the left-most column if this property is null, otherwise it will be the specified column assuming it is non-null and contained within the `visible leaf columns` list.
    See Also:
      `getTreeColumn()`, `setTreeColumn(TreeTableColumn)`

  - ### selectionModel

    public final ObjectProperty<TreeTableView.TreeTableViewSelectionModel<S>> selectionModelProperty
    The SelectionModel provides the API through which it is possible to select single or multiple items within a TreeTableView, as well as inspect which rows have been selected by the user. Note that it has a generic type that must match the type of the TreeTableView itself.
    See Also:
      `getSelectionModel()`, `setSelectionModel(TreeTableView.TreeTableViewSelectionModel)`

  - ### focusModel

    public final ObjectProperty<TreeTableView.TreeTableViewFocusModel<S>> focusModelProperty
    The FocusModel provides the API through which it is possible to control focus on zero or one rows of the TreeTableView. Generally the default implementation should be more than sufficient.
    See Also:
      `getFocusModel()`, `setFocusModel(TreeTableView.TreeTableViewFocusModel)`

  - ### expandedItemCount

    public final ReadOnlyIntegerProperty expandedItemCountProperty

    Represents the number of tree nodes presently able to be visible in the TreeTableView. This is essentially the count of all expanded tree items, and their children.

    For example, if just the root node is visible, the expandedItemCount will be one. If the root had three children and the root was expanded, the value will be four.

    See Also:
      `getExpandedItemCount()`

  - ### editable

    public final BooleanProperty editableProperty
    Specifies whether this TreeTableView is editable - only if the TreeTableView and the TreeCells within it are both editable will a TreeCell be able to go into their editing state.
    See Also:
      `isEditable()`, `setEditable(boolean)`

  - ### editingCell

    public final ReadOnlyObjectProperty<TreeTablePosition<S,​?>> editingCellProperty
    Represents the current cell being edited, or null if there is no cell being edited.
    See Also:
      `getEditingCell()`

  - ### tableMenuButtonVisible

    public final BooleanProperty tableMenuButtonVisibleProperty
    This controls whether a menu button is available when the user clicks in a designated space within the TableView, within which is a radio menu item for each TreeTableColumn in this table. This menu allows for the user to show and hide all TreeTableColumns easily.
    See Also:
      `isTableMenuButtonVisible()`, `setTableMenuButtonVisible(boolean)`

  - ### columnResizePolicy

    public final ObjectProperty<Callback<TreeTableView.ResizeFeatures,​Boolean>> columnResizePolicyProperty
    This is the function called when the user completes a column-resize operation. The two most common policies are available as static functions in the TableView class: `UNCONSTRAINED_RESIZE_POLICY` and `CONSTRAINED_RESIZE_POLICY`.
    See Also:
      `getColumnResizePolicy()`, `setColumnResizePolicy(Callback)`

  - ### rowFactory

    public final ObjectProperty<Callback<TreeTableView<S>,​TreeTableRow<S>>> rowFactoryProperty
    A function which produces a TreeTableRow. The system is responsible for reusing TreeTableRows. Return from this function a TreeTableRow which might be usable for representing a single row in a TableView.

    Note that a TreeTableRow is not a TableCell. A TreeTableRow is simply a container for a TableCell, and in most circumstances it is more likely that you'll want to create custom TableCells, rather than TreeTableRows. The primary use case for creating custom TreeTableRow instances would most probably be to introduce some form of column spanning support.

    You can create custom TableCell instances per column by assigning the appropriate function to the cellFactory property in the TreeTableColumn class.

    See Also:
      `getRowFactory()`, `setRowFactory(Callback)`

  - ### placeholder

    public final ObjectProperty<Node> placeholderProperty
    This Node is shown to the user when the table has no content to show. This may be the case because the table model has no data in the first place, that a filter has been applied to the table model, resulting in there being nothing to show the user, or that there are no currently visible columns.
    See Also:
      `getPlaceholder()`, `setPlaceholder(Node)`

  - ### fixedCellSize

    public final DoubleProperty fixedCellSizeProperty
    Specifies whether this control has cells that are a fixed height (of the specified value). If this value is less than or equal to zero, then all cells are individually sized and positioned. This is a slow operation. Therefore, when performance matters and developers are not dependent on variable cell sizes it is a good idea to set the fixed cell size value. Generally cells are around 24px, so setting a fixed cell size of 24 is likely to result in very little difference in visuals, but a improvement to performance.

    To set this property via CSS, use the -fx-fixed-cell-size property. This should not be confused with the -fx-cell-size property. The difference between these two CSS properties is that -fx-cell-size will size all cells to the specified size, but it will not enforce that this is the only size (thus allowing for variable cell sizes, and preventing the performance gains from being possible). Therefore, when performance matters use -fx-fixed-cell-size, instead of -fx-cell-size. If both properties are specified in CSS, -fx-fixed-cell-size takes precedence.

    Since:
      JavaFX 8.0
    See Also:
      `getFixedCellSize()`, `setFixedCellSize(double)`

  - ### sortMode

    public final ObjectProperty<TreeSortMode> sortModeProperty
    Specifies the sort mode to use when sorting the contents of this TreeTableView, should any columns be specified in the `sort order` list.
    See Also:
      `getSortMode()`, `setSortMode(TreeSortMode)`

  - ### comparator

    public final ReadOnlyObjectProperty<Comparator<TreeItem<S>>> comparatorProperty
    The comparator property is a read-only property that is representative of the current state of the `sort order` list. The sort order list contains the columns that have been added to it either programmatically or via a user clicking on the headers themselves.
    See Also:
      `getComparator()`

  - ### sortPolicy

    public final ObjectProperty<Callback<TreeTableView<S>,​Boolean>> sortPolicyProperty
    The sort policy specifies how sorting in this TreeTableView should be performed. For example, a basic sort policy may just recursively sort the children of the root tree item, whereas a more advanced sort policy may call to a database to perform the necessary sorting on the server-side.

    TreeTableView ships with a `default sort policy` that does precisely as mentioned above: it simply attempts to sort the tree hierarchy in-place.

    It is recommended that rather than override the `sort` method that a different sort policy be provided instead.

    See Also:
      `getSortPolicy()`, `setSortPolicy(Callback)`

  - ### onSort

    public ObjectProperty<EventHandler<SortEvent<TreeTableView<S>>>> onSortProperty
    Called when there's a request to sort the control.
    See Also:
      `getOnSort()`, `setOnSort(EventHandler)`

  - ### onScrollTo

    public ObjectProperty<EventHandler<ScrollToEvent<Integer>>> onScrollToProperty
    Called when there's a request to scroll an index into view using `scrollTo(int)`
    See Also:
      `getOnScrollTo()`, `setOnScrollTo(EventHandler)`

  - ### onScrollToColumn

    public ObjectProperty<EventHandler<ScrollToEvent<TreeTableColumn<S,​?>>>> onScrollToColumnProperty
    Called when there's a request to scroll a column into view using `scrollToColumn(TreeTableColumn)` or `scrollToColumnIndex(int)`
    See Also:
      `getOnScrollToColumn()`, `setOnScrollToColumn(EventHandler)`

- ## Field Details

  - ### UNCONSTRAINED_RESIZE_POLICY

    public static final Callback<TreeTableView.ResizeFeatures,​Boolean> UNCONSTRAINED_RESIZE_POLICY

    Very simple resize policy that just resizes the specified column by the provided delta and shifts all other columns (to the right of the given column) further to the right (when the delta is positive) or to the left (when the delta is negative).

    It also handles the case where we have nested columns by sharing the new space, or subtracting the removed space, evenly between all immediate children columns. Of course, the immediate children may themselves be nested, and they would then use this policy on their children.

  - ### CONSTRAINED_RESIZE_POLICY

    public static final Callback<TreeTableView.ResizeFeatures,​Boolean> CONSTRAINED_RESIZE_POLICY

    Simple policy that ensures the width of all visible leaf columns in this table sum up to equal the width of the table itself.

    When the user resizes a column width with this policy, the table automatically adjusts the width of the right hand side columns. When the user increases a column width, the table decreases the width of the rightmost column until it reaches its minimum width. Then it decreases the width of the second rightmost column until it reaches minimum width and so on. When all right hand side columns reach minimum size, the user cannot increase the size of resized column any more.

  - ### DEFAULT_SORT_POLICY

    public static final Callback<TreeTableView,​Boolean> DEFAULT_SORT_POLICY
    The default `sort policy` that this TreeTableView will use if no other policy is specified. The sort policy is a simple `Callback` that accepts a TreeTableView as the sole argument and expects a Boolean response representing whether the sort succeeded or not. A Boolean response of true represents success, and a response of false (or null) will be considered to represent failure.

- ## Constructor Details

  - ### TreeTableView

    public TreeTableView()
    Creates an empty TreeTableView.

    Refer to the `TreeTableView` class documentation for details on the default state of other properties.

  - ### TreeTableView

    public TreeTableView​(TreeItem<S> root)
    Creates a TreeTableView with the provided root node.

    Refer to the `TreeTableView` class documentation for details on the default state of other properties.

    Parameters:
      `root` - The node to be the root in this TreeTableView.

- ## Method Details

  - ### editAnyEvent

    public static <S> EventType<TreeTableView.EditEvent<S>> editAnyEvent()
    An EventType that indicates some edit event has occurred. It is the parent type of all other edit events: `editStartEvent()`, `editCommitEvent()` and `editCancelEvent()`.
    Type Parameters:
      `S` - The type of the TreeItem instances used in this TreeTableView
    Returns:
      An EventType that indicates some edit event has occurred

  - ### editStartEvent

    public static <S> EventType<TreeTableView.EditEvent<S>> editStartEvent()
    An EventType used to indicate that an edit event has started within the TreeTableView upon which the event was fired.
    Type Parameters:
      `S` - The type of the TreeItem instances used in this TreeTableView
    Returns:
      An EventType used to indicate that an edit event has started

  - ### editCancelEvent

    public static <S> EventType<TreeTableView.EditEvent<S>> editCancelEvent()
    An EventType used to indicate that an edit event has just been canceled within the TreeTableView upon which the event was fired.
    Type Parameters:
      `S` - The type of the TreeItem instances used in this TreeTableView
    Returns:
      An EventType used to indicate that an edit event has just been canceled

  - ### editCommitEvent

    public static <S> EventType<TreeTableView.EditEvent<S>> editCommitEvent()
    An EventType that is used to indicate that an edit in a TreeTableView has been committed. This means that user has made changes to the data of a TreeItem, and that the UI should be updated.
    Type Parameters:
      `S` - The type of the TreeItem instances used in this TreeTableView
    Returns:
      An EventType that is used to indicate that an edit in a TreeTableView has been committed

  - ### getNodeLevel

    @Deprecated(since="8u20") public static int getNodeLevel​(TreeItem<?> node)
    Deprecated.
    This method does not correctly calculate the distance from the given TreeItem to the root of the TreeTableView. As of JavaFX 8.0_20, the proper way to do this is via `getTreeItemLevel(TreeItem)`
    Returns the number of levels of 'indentation' of the given TreeItem, based on how many times `TreeItem.getParent()` can be recursively called. If the TreeItem does not have any parent set, the returned value will be zero. For each time getParent() is recursively called, the returned value is incremented by one.

    Important note: This method is deprecated as it does not consider the root node. This means that this method will iterate past the root node of the TreeTableView control, if the root node has a parent. If this is important, call `getTreeItemLevel(TreeItem)` instead.

    Parameters:
      `node` - The TreeItem for which the level is needed.
    Returns:
      An integer representing the number of parents above the given node, or -1 if the given TreeItem is null.

  - ### setRoot

    public final void setRoot​(TreeItem<S> value)
    Sets the root node in this TreeTableView. See the `TreeItem` class level documentation for more details.
    Parameters:
      `value` - The `TreeItem` that will be placed at the root of the TreeTableView.

  - ### getRoot

    public final TreeItem<S> getRoot()
    Returns the current root node of this TreeTableView, or null if no root node is specified.
    Returns:
      The current root node, or null if no root node exists.

  - ### rootProperty

    public final ObjectProperty<TreeItem<S>> rootProperty()
    Property representing the root node of the TreeTableView.
    Returns:
      the root property

  - ### setShowRoot

    public final void setShowRoot​(boolean value)
    Specifies whether the root `TreeItem` should be shown within this TreeTableView.
    Parameters:
      `value` - If true, the root TreeItem will be shown, and if false it will be hidden.

  - ### isShowRoot

    public final boolean isShowRoot()
    Returns true if the root of the TreeTableView should be shown, and false if it should not. By default, the root TreeItem is visible in the TreeTableView.
    Returns:
      true if the root of the TreeTableView should be shown

  - ### showRootProperty

    public final BooleanProperty showRootProperty()
    Property that represents whether or not the TreeTableView root node is visible.
    See Also:
      `isShowRoot()`, `setShowRoot(boolean)`

  - ### treeColumnProperty

    public final ObjectProperty<TreeTableColumn<S,​?>> treeColumnProperty()
    Property that represents which column should have the disclosure node shown in it (that is, the column with the arrow). By default this will be the left-most column if this property is null, otherwise it will be the specified column assuming it is non-null and contained within the `visible leaf columns` list.
    See Also:
      `getTreeColumn()`, `setTreeColumn(TreeTableColumn)`

  - ### setTreeColumn

    public final void setTreeColumn​(TreeTableColumn<S,​?> value)
    Sets the value of the property treeColumn.
    Property description:
      Property that represents which column should have the disclosure node shown in it (that is, the column with the arrow). By default this will be the left-most column if this property is null, otherwise it will be the specified column assuming it is non-null and contained within the `visible leaf columns` list.

  - ### getTreeColumn

    public final TreeTableColumn<S,​?> getTreeColumn()
    Gets the value of the property treeColumn.
    Property description:
      Property that represents which column should have the disclosure node shown in it (that is, the column with the arrow). By default this will be the left-most column if this property is null, otherwise it will be the specified column assuming it is non-null and contained within the `visible leaf columns` list.

  - ### setSelectionModel

    public final void setSelectionModel​(TreeTableView.TreeTableViewSelectionModel<S> value)
    Sets the `MultipleSelectionModel` to be used in the TreeTableView. Despite a TreeTableView requiring a `MultipleSelectionModel`, it is possible to configure it to only allow single selection (see `MultipleSelectionModel.setSelectionMode(javafx.scene.control.SelectionMode)` for more information).
    Parameters:
      `value` - the `MultipleSelectionModel` to be used

  - ### getSelectionModel

    public final TreeTableView.TreeTableViewSelectionModel<S> getSelectionModel()
    Returns the currently installed selection model.
    Returns:
      the currently installed selection model

  - ### selectionModelProperty

    public final ObjectProperty<TreeTableView.TreeTableViewSelectionModel<S>> selectionModelProperty()
    The SelectionModel provides the API through which it is possible to select single or multiple items within a TreeTableView, as well as inspect which rows have been selected by the user. Note that it has a generic type that must match the type of the TreeTableView itself.
    See Also:
      `getSelectionModel()`, `setSelectionModel(TreeTableView.TreeTableViewSelectionModel)`

  - ### setFocusModel

    public final void setFocusModel​(TreeTableView.TreeTableViewFocusModel<S> value)
    Sets the `FocusModel` to be used in the TreeTableView.
    Parameters:
      `value` - the `FocusModel` to be used

  - ### getFocusModel

    public final TreeTableView.TreeTableViewFocusModel<S> getFocusModel()
    Returns the currently installed `FocusModel`.
    Returns:
      the currently installed `FocusModel`

  - ### focusModelProperty

    public final ObjectProperty<TreeTableView.TreeTableViewFocusModel<S>> focusModelProperty()
    The FocusModel provides the API through which it is possible to control focus on zero or one rows of the TreeTableView. Generally the default implementation should be more than sufficient.
    See Also:
      `getFocusModel()`, `setFocusModel(TreeTableView.TreeTableViewFocusModel)`

  - ### expandedItemCountProperty

    public final ReadOnlyIntegerProperty expandedItemCountProperty()

    Represents the number of tree nodes presently able to be visible in the TreeTableView. This is essentially the count of all expanded tree items, and their children.

    For example, if just the root node is visible, the expandedItemCount will be one. If the root had three children and the root was expanded, the value will be four.

    See Also:
      `getExpandedItemCount()`

  - ### getExpandedItemCount

    public final int getExpandedItemCount()
    Gets the value of the property expandedItemCount.
    Property description:

      Represents the number of tree nodes presently able to be visible in the TreeTableView. This is essentially the count of all expanded tree items, and their children.

      For example, if just the root node is visible, the expandedItemCount will be one. If the root had three children and the root was expanded, the value will be four.

  - ### setEditable

    public final void setEditable​(boolean value)
    Sets the value of the property editable.
    Property description:
      Specifies whether this TreeTableView is editable - only if the TreeTableView and the TreeCells within it are both editable will a TreeCell be able to go into their editing state.

  - ### isEditable

    public final boolean isEditable()
    Gets the value of the property editable.
    Property description:
      Specifies whether this TreeTableView is editable - only if the TreeTableView and the TreeCells within it are both editable will a TreeCell be able to go into their editing state.

  - ### editableProperty

    public final BooleanProperty editableProperty()
    Specifies whether this TreeTableView is editable - only if the TreeTableView and the TreeCells within it are both editable will a TreeCell be able to go into their editing state.
    See Also:
      `isEditable()`, `setEditable(boolean)`

  - ### getEditingCell

    public final TreeTablePosition<S,​?> getEditingCell()
    Gets the value of the property editingCell.
    Property description:
      Represents the current cell being edited, or null if there is no cell being edited.

  - ### editingCellProperty

    public final ReadOnlyObjectProperty<TreeTablePosition<S,​?>> editingCellProperty()
    Represents the current cell being edited, or null if there is no cell being edited.
    See Also:
      `getEditingCell()`

  - ### tableMenuButtonVisibleProperty

    public final BooleanProperty tableMenuButtonVisibleProperty()
    This controls whether a menu button is available when the user clicks in a designated space within the TableView, within which is a radio menu item for each TreeTableColumn in this table. This menu allows for the user to show and hide all TreeTableColumns easily.
    See Also:
      `isTableMenuButtonVisible()`, `setTableMenuButtonVisible(boolean)`

  - ### setTableMenuButtonVisible

    public final void setTableMenuButtonVisible​(boolean value)
    Sets the value of the property tableMenuButtonVisible.
    Property description:
      This controls whether a menu button is available when the user clicks in a designated space within the TableView, within which is a radio menu item for each TreeTableColumn in this table. This menu allows for the user to show and hide all TreeTableColumns easily.

  - ### isTableMenuButtonVisible

    public final boolean isTableMenuButtonVisible()
    Gets the value of the property tableMenuButtonVisible.
    Property description:
      This controls whether a menu button is available when the user clicks in a designated space within the TableView, within which is a radio menu item for each TreeTableColumn in this table. This menu allows for the user to show and hide all TreeTableColumns easily.

  - ### setColumnResizePolicy

    public final void setColumnResizePolicy​(Callback<TreeTableView.ResizeFeatures,​Boolean> callback)
    Sets the value of the property columnResizePolicy.
    Property description:
      This is the function called when the user completes a column-resize operation. The two most common policies are available as static functions in the TableView class: `UNCONSTRAINED_RESIZE_POLICY` and `CONSTRAINED_RESIZE_POLICY`.

  - ### getColumnResizePolicy

    public final Callback<TreeTableView.ResizeFeatures,​Boolean> getColumnResizePolicy()
    Gets the value of the property columnResizePolicy.
    Property description:
      This is the function called when the user completes a column-resize operation. The two most common policies are available as static functions in the TableView class: `UNCONSTRAINED_RESIZE_POLICY` and `CONSTRAINED_RESIZE_POLICY`.

  - ### columnResizePolicyProperty

    public final ObjectProperty<Callback<TreeTableView.ResizeFeatures,​Boolean>> columnResizePolicyProperty()
    This is the function called when the user completes a column-resize operation. The two most common policies are available as static functions in the TableView class: `UNCONSTRAINED_RESIZE_POLICY` and `CONSTRAINED_RESIZE_POLICY`.
    See Also:
      `getColumnResizePolicy()`, `setColumnResizePolicy(Callback)`

  - ### rowFactoryProperty

    public final ObjectProperty<Callback<TreeTableView<S>,​TreeTableRow<S>>> rowFactoryProperty()
    A function which produces a TreeTableRow. The system is responsible for reusing TreeTableRows. Return from this function a TreeTableRow which might be usable for representing a single row in a TableView.

    Note that a TreeTableRow is not a TableCell. A TreeTableRow is simply a container for a TableCell, and in most circumstances it is more likely that you'll want to create custom TableCells, rather than TreeTableRows. The primary use case for creating custom TreeTableRow instances would most probably be to introduce some form of column spanning support.

    You can create custom TableCell instances per column by assigning the appropriate function to the cellFactory property in the TreeTableColumn class.

    See Also:
      `getRowFactory()`, `setRowFactory(Callback)`

  - ### setRowFactory

    public final void setRowFactory​(Callback<TreeTableView<S>,​TreeTableRow<S>> value)
    Sets the value of the property rowFactory.
    Property description:
      A function which produces a TreeTableRow. The system is responsible for reusing TreeTableRows. Return from this function a TreeTableRow which might be usable for representing a single row in a TableView.

      Note that a TreeTableRow is not a TableCell. A TreeTableRow is simply a container for a TableCell, and in most circumstances it is more likely that you'll want to create custom TableCells, rather than TreeTableRows. The primary use case for creating custom TreeTableRow instances would most probably be to introduce some form of column spanning support.

      You can create custom TableCell instances per column by assigning the appropriate function to the cellFactory property in the TreeTableColumn class.

  - ### getRowFactory

    public final Callback<TreeTableView<S>,​TreeTableRow<S>> getRowFactory()
    Gets the value of the property rowFactory.
    Property description:
      A function which produces a TreeTableRow. The system is responsible for reusing TreeTableRows. Return from this function a TreeTableRow which might be usable for representing a single row in a TableView.

      Note that a TreeTableRow is not a TableCell. A TreeTableRow is simply a container for a TableCell, and in most circumstances it is more likely that you'll want to create custom TableCells, rather than TreeTableRows. The primary use case for creating custom TreeTableRow instances would most probably be to introduce some form of column spanning support.

      You can create custom TableCell instances per column by assigning the appropriate function to the cellFactory property in the TreeTableColumn class.

  - ### placeholderProperty

    public final ObjectProperty<Node> placeholderProperty()
    This Node is shown to the user when the table has no content to show. This may be the case because the table model has no data in the first place, that a filter has been applied to the table model, resulting in there being nothing to show the user, or that there are no currently visible columns.
    See Also:
      `getPlaceholder()`, `setPlaceholder(Node)`

  - ### setPlaceholder

    public final void setPlaceholder​(Node value)
    Sets the value of the property placeholder.
    Property description:
      This Node is shown to the user when the table has no content to show. This may be the case because the table model has no data in the first place, that a filter has been applied to the table model, resulting in there being nothing to show the user, or that there are no currently visible columns.

  - ### getPlaceholder

    public final Node getPlaceholder()
    Gets the value of the property placeholder.
    Property description:
      This Node is shown to the user when the table has no content to show. This may be the case because the table model has no data in the first place, that a filter has been applied to the table model, resulting in there being nothing to show the user, or that there are no currently visible columns.

  - ### setFixedCellSize

    public final void setFixedCellSize​(double value)
    Sets the new fixed cell size for this control. Any value greater than zero will enable fixed cell size mode, whereas a zero or negative value (or Region.USE_COMPUTED_SIZE) will be used to disabled fixed cell size mode.
    Parameters:
      `value` - The new fixed cell size value, or a value less than or equal to zero (or Region.USE_COMPUTED_SIZE) to disable.
    Since:
      JavaFX 8.0

  - ### getFixedCellSize

    public final double getFixedCellSize()
    Returns the fixed cell size value. A value less than or equal to zero is used to represent that fixed cell size mode is disabled, and a value greater than zero represents the size of all cells in this control.
    Returns:
      A double representing the fixed cell size of this control, or a value less than or equal to zero if fixed cell size mode is disabled.
    Since:
      JavaFX 8.0

  - ### fixedCellSizeProperty

    public final DoubleProperty fixedCellSizeProperty()
    Specifies whether this control has cells that are a fixed height (of the specified value). If this value is less than or equal to zero, then all cells are individually sized and positioned. This is a slow operation. Therefore, when performance matters and developers are not dependent on variable cell sizes it is a good idea to set the fixed cell size value. Generally cells are around 24px, so setting a fixed cell size of 24 is likely to result in very little difference in visuals, but a improvement to performance.

    To set this property via CSS, use the -fx-fixed-cell-size property. This should not be confused with the -fx-cell-size property. The difference between these two CSS properties is that -fx-cell-size will size all cells to the specified size, but it will not enforce that this is the only size (thus allowing for variable cell sizes, and preventing the performance gains from being possible). Therefore, when performance matters use -fx-fixed-cell-size, instead of -fx-cell-size. If both properties are specified in CSS, -fx-fixed-cell-size takes precedence.

    Since:
      JavaFX 8.0
    See Also:
      `getFixedCellSize()`, `setFixedCellSize(double)`

  - ### sortModeProperty

    public final ObjectProperty<TreeSortMode> sortModeProperty()
    Specifies the sort mode to use when sorting the contents of this TreeTableView, should any columns be specified in the `sort order` list.
    See Also:
      `getSortMode()`, `setSortMode(TreeSortMode)`

  - ### setSortMode

    public final void setSortMode​(TreeSortMode value)
    Sets the value of the property sortMode.
    Property description:
      Specifies the sort mode to use when sorting the contents of this TreeTableView, should any columns be specified in the `sort order` list.

  - ### getSortMode

    public final TreeSortMode getSortMode()
    Gets the value of the property sortMode.
    Property description:
      Specifies the sort mode to use when sorting the contents of this TreeTableView, should any columns be specified in the `sort order` list.

  - ### getComparator

    public final Comparator<TreeItem<S>> getComparator()
    Gets the value of the property comparator.
    Property description:
      The comparator property is a read-only property that is representative of the current state of the `sort order` list. The sort order list contains the columns that have been added to it either programmatically or via a user clicking on the headers themselves.

  - ### comparatorProperty

    public final ReadOnlyObjectProperty<Comparator<TreeItem<S>>> comparatorProperty()
    The comparator property is a read-only property that is representative of the current state of the `sort order` list. The sort order list contains the columns that have been added to it either programmatically or via a user clicking on the headers themselves.
    See Also:
      `getComparator()`

  - ### setSortPolicy

    public final void setSortPolicy​(Callback<TreeTableView<S>,​Boolean> callback)
    Sets the value of the property sortPolicy.
    Property description:
      The sort policy specifies how sorting in this TreeTableView should be performed. For example, a basic sort policy may just recursively sort the children of the root tree item, whereas a more advanced sort policy may call to a database to perform the necessary sorting on the server-side.

      TreeTableView ships with a `default sort policy` that does precisely as mentioned above: it simply attempts to sort the tree hierarchy in-place.

      It is recommended that rather than override the `sort` method that a different sort policy be provided instead.

  - ### getSortPolicy

    public final Callback<TreeTableView<S>,​Boolean> getSortPolicy()
    Gets the value of the property sortPolicy.
    Property description:
      The sort policy specifies how sorting in this TreeTableView should be performed. For example, a basic sort policy may just recursively sort the children of the root tree item, whereas a more advanced sort policy may call to a database to perform the necessary sorting on the server-side.

      TreeTableView ships with a `default sort policy` that does precisely as mentioned above: it simply attempts to sort the tree hierarchy in-place.

      It is recommended that rather than override the `sort` method that a different sort policy be provided instead.

  - ### sortPolicyProperty

    public final ObjectProperty<Callback<TreeTableView<S>,​Boolean>> sortPolicyProperty()
    The sort policy specifies how sorting in this TreeTableView should be performed. For example, a basic sort policy may just recursively sort the children of the root tree item, whereas a more advanced sort policy may call to a database to perform the necessary sorting on the server-side.

    TreeTableView ships with a `default sort policy` that does precisely as mentioned above: it simply attempts to sort the tree hierarchy in-place.

    It is recommended that rather than override the `sort` method that a different sort policy be provided instead.

    See Also:
      `getSortPolicy()`, `setSortPolicy(Callback)`

  - ### setOnSort

    public void setOnSort​(EventHandler<SortEvent<TreeTableView<S>>> value)
    Sets the value of the property onSort.
    Property description:
      Called when there's a request to sort the control.

  - ### getOnSort

    public EventHandler<SortEvent<TreeTableView<S>>> getOnSort()
    Gets the value of the property onSort.
    Property description:
      Called when there's a request to sort the control.

  - ### onSortProperty

    public ObjectProperty<EventHandler<SortEvent<TreeTableView<S>>>> onSortProperty()
    Called when there's a request to sort the control.
    See Also:
      `getOnSort()`, `setOnSort(EventHandler)`

  - ### layoutChildren

    protected void layoutChildren()
    Invoked during the layout pass to layout the children in this `Parent`. By default it will only set the size of managed, resizable content to their preferred sizes and does not do any node positioning.

    Subclasses should override this function to layout content as needed.

    Overrides:
      `layoutChildren` in class `Control`

  - ### scrollTo

    public void scrollTo​(int index)
    Scrolls the TreeTableView such that the item in the given index is visible to the end user.
    Parameters:
      `index` - The index that should be made visible to the user, assuming of course that it is greater than, or equal to 0, and less than the number of the visible items in the TreeTableView.

  - ### setOnScrollTo

    public void setOnScrollTo​(EventHandler<ScrollToEvent<Integer>> value)
    Sets the value of the property onScrollTo.
    Property description:
      Called when there's a request to scroll an index into view using `scrollTo(int)`

  - ### getOnScrollTo

    public EventHandler<ScrollToEvent<Integer>> getOnScrollTo()
    Gets the value of the property onScrollTo.
    Property description:
      Called when there's a request to scroll an index into view using `scrollTo(int)`

  - ### onScrollToProperty

    public ObjectProperty<EventHandler<ScrollToEvent<Integer>>> onScrollToProperty()
    Called when there's a request to scroll an index into view using `scrollTo(int)`
    See Also:
      `getOnScrollTo()`, `setOnScrollTo(EventHandler)`

  - ### scrollToColumn

    public void scrollToColumn​(TreeTableColumn<S,​?> column)
    Scrolls the TreeTableView so that the given column is visible within the viewport.
    Parameters:
      `column` - The column that should be visible to the user.

  - ### scrollToColumnIndex

    public void scrollToColumnIndex​(int columnIndex)
    Scrolls the TreeTableView so that the given index is visible within the viewport.
    Parameters:
      `columnIndex` - The index of a column that should be visible to the user.

  - ### setOnScrollToColumn

    public void setOnScrollToColumn​(EventHandler<ScrollToEvent<TreeTableColumn<S,​?>>> value)
    Sets the value of the property onScrollToColumn.
    Property description:
      Called when there's a request to scroll a column into view using `scrollToColumn(TreeTableColumn)` or `scrollToColumnIndex(int)`

  - ### getOnScrollToColumn

    public EventHandler<ScrollToEvent<TreeTableColumn<S,​?>>> getOnScrollToColumn()
    Gets the value of the property onScrollToColumn.
    Property description:
      Called when there's a request to scroll a column into view using `scrollToColumn(TreeTableColumn)` or `scrollToColumnIndex(int)`

  - ### onScrollToColumnProperty

    public ObjectProperty<EventHandler<ScrollToEvent<TreeTableColumn<S,​?>>>> onScrollToColumnProperty()
    Called when there's a request to scroll a column into view using `scrollToColumn(TreeTableColumn)` or `scrollToColumnIndex(int)`
    See Also:
      `getOnScrollToColumn()`, `setOnScrollToColumn(EventHandler)`

  - ### getRow

    public int getRow​(TreeItem<S> item)
    Returns the index position of the given TreeItem, assuming that it is currently accessible through the tree hierarchy (most notably, that all parent tree items are expanded). If a parent tree item is collapsed, the result is that this method will return -1 to indicate that the given tree item is not accessible in the tree.
    Parameters:
      `item` - The TreeItem for which the index is sought.
    Returns:
      An integer representing the location in the current TreeTableView of the first instance of the given TreeItem, or -1 if it is null or can not be found (for example, if a parent (all the way up to the root) is collapsed).

  - ### getTreeItem

    public TreeItem<S> getTreeItem​(int row)
    Returns the TreeItem in the given index, or null if it is out of bounds.
    Parameters:
      `row` - The index of the TreeItem being sought.
    Returns:
      The TreeItem in the given index, or null if it is out of bounds.

  - ### getTreeItemLevel

    public int getTreeItemLevel​(TreeItem<?> node)
    Returns the number of levels of 'indentation' of the given TreeItem, based on how many times getParent() can be recursively called. If the given TreeItem is the root node of this TreeTableView, or if the TreeItem does not have any parent set, the returned value will be zero. For each time getParent() is recursively called, the returned value is incremented by one.
    Parameters:
      `node` - The TreeItem for which the level is needed.
    Returns:
      An integer representing the number of parents above the given node, or -1 if the given TreeItem is null.

  - ### getColumns

    public final ObservableList<TreeTableColumn<S,​?>> getColumns()
    The TreeTableColumns that are part of this TableView. As the user reorders the TableView columns, this list will be updated to reflect the current visual ordering.

    Note: to display any data in a TableView, there must be at least one TreeTableColumn in this ObservableList.

    Returns:
      the table table column

  - ### getSortOrder

    public final ObservableList<TreeTableColumn<S,​?>> getSortOrder()
    The sortOrder list defines the order in which `TreeTableColumn` instances are sorted. An empty sortOrder list means that no sorting is being applied on the TableView. If the sortOrder list has one TreeTableColumn within it, the TableView will be sorted using the `sortType` and `comparator` properties of this TreeTableColumn (assuming `TreeTableColumn.sortable` is true). If the sortOrder list contains multiple TreeTableColumn instances, then the TableView is firstly sorted based on the properties of the first TreeTableColumn. If two elements are considered equal, then the second TreeTableColumn in the list is used to determine ordering. This repeats until the results from all TreeTableColumn comparators are considered, if necessary.
    Returns:
      An ObservableList containing zero or more TreeTableColumn instances.

  - ### resizeColumn

    public boolean resizeColumn​(TreeTableColumn<S,​?> column, double delta)
    Applies the currently installed resize policy against the given column, resizing it based on the delta value provided.
    Parameters:
      `column` - the column
      `delta` - the delta
    Returns:
      true if column resizing is applied

  - ### edit

    public void edit​(int row, TreeTableColumn<S,​?> column)
    Causes the cell at the given row/column view indexes to switch into its editing state, if it is not already in it, and assuming that the TableView and column are also editable.
    Parameters:
      `row` - the row
      `column` - the column

  - ### getVisibleLeafColumns

    public ObservableList<TreeTableColumn<S,​?>> getVisibleLeafColumns()
    Returns an unmodifiable list containing the currently visible leaf columns.
    Returns:
      an unmodifiable list containing the currently visible leaf columns

  - ### getVisibleLeafIndex

    public int getVisibleLeafIndex​(TreeTableColumn<S,​?> column)
    Returns the position of the given column, relative to all other visible leaf columns.
    Parameters:
      `column` - the column
    Returns:
      the position of the given column, relative to all other visible leaf columns

  - ### getVisibleLeafColumn

    public TreeTableColumn<S,​?> getVisibleLeafColumn​(int column)
    Returns the TreeTableColumn in the given column index, relative to all other visible leaf columns.
    Parameters:
      `column` - the column
    Returns:
      the TreeTableColumn in the given column index, relative to all other visible leaf columns

  - ### sort

    public void sort()
    The sort method forces the TreeTableView to re-run its sorting algorithm. More often than not it is not necessary to call this method directly, as it is automatically called when the `sort order`, `sort policy`, or the state of the TreeTableColumn `sort type` properties change. In other words, this method should only be called directly when something external changes and a sort is required.

  - ### refresh

    public void refresh()
    Calling `refresh()` forces the TreeTableView control to recreate and repopulate the cells necessary to populate the visual bounds of the control. In other words, this forces the TreeTableView to update what it is showing to the user. This is useful in cases where the underlying data source has changed in a way that is not observed by the TreeTableView itself.
    Since:
      JavaFX 8u60

  - ### getClassCssMetaData

    public static List<CssMetaData<? extends Styleable,​?>> getClassCssMetaData()
    Returns:
      The CssMetaData associated with this class, which may include the CssMetaData of its superclasses.

  - ### getControlCssMetaData

    public List<CssMetaData<? extends Styleable,​?>> getControlCssMetaData()
    Overrides:
      `getControlCssMetaData` in class `Control`
    Returns:
      unmodifiable list of the controls css styleable properties
    Since:
      JavaFX 8.0

  - ### createDefaultSkin

    protected Skin<?> createDefaultSkin()
    Create a new instance of the default skin for this control. This is called to create a skin for the control if no skin is provided via CSS `-fx-skin` or set explicitly in a sub-class with `setSkin(...)`.
    Overrides:
      `createDefaultSkin` in class `Control`
    Returns:
      new instance of default skin for this control. If null then the control will have no skin unless one is provided by css.

  - ### queryAccessibleAttribute

    public Object queryAccessibleAttribute​(AccessibleAttribute attribute, Object... parameters)
    This method is called by the assistive technology to request the value for an attribute.

    This method is commonly overridden by subclasses to implement attributes that are required for a specific role.
    If a particular attribute is not handled, the superclass implementation must be called.

    Overrides:
      `queryAccessibleAttribute` in class `Control`
    Parameters:
      `attribute` - the requested attribute
      `parameters` - optional list of parameters
    Returns:
      the value for the requested attribute
    See Also:
      `AccessibleAttribute`