BasicTreeUI (Java Platform SE 8 )
Keywords: javax.swing.plaf.basic.BasicTreeUI class
Date: 2026-04-22

javax.swing.plaf.basic

## Class BasicTreeUI

- java.lang.Object
- - javax.swing.plaf.ComponentUI
  - - javax.swing.plaf.TreeUI
    - - javax.swing.plaf.basic.BasicTreeUI

- Direct Known Subclasses:
    MetalTreeUI, SynthTreeUI

      public class BasicTreeUI
      extends TreeUI

  The basic L&F for a hierarchical data structure.

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `class` | `BasicTreeUI.CellEditorHandler` Listener responsible for getting cell editing events and updating the tree accordingly.
    `class` | `BasicTreeUI.ComponentHandler` Updates the preferred size when scrolling (if necessary).
    `class` | `BasicTreeUI.FocusHandler` Repaints the lead selection row when focus is lost/gained.
    `class` | `BasicTreeUI.KeyHandler` This is used to get multiple key down events to appropriately generate events.
    `class` | `BasicTreeUI.MouseHandler` TreeMouseListener is responsible for updating the selection based on mouse events.
    `class` | `BasicTreeUI.MouseInputHandler` MouseInputHandler handles passing all mouse events, including mouse motion events, until the mouse is released to the destination it is constructed with.
    `class` | `BasicTreeUI.NodeDimensionsHandler` Class responsible for getting size of node, method is forwarded to BasicTreeUI method.
    `class` | `BasicTreeUI.PropertyChangeHandler` PropertyChangeListener for the tree.
    `class` | `BasicTreeUI.SelectionModelPropertyChangeHandler` Listener on the TreeSelectionModel, resets the row selection if any of the properties of the model change.
    `class` | `BasicTreeUI.TreeCancelEditingAction` ActionListener that invokes cancelEditing when action performed.
    `class` | `BasicTreeUI.TreeExpansionHandler` Updates the TreeState in response to nodes expanding/collapsing.
    `class` | `BasicTreeUI.TreeHomeAction` TreeHomeAction is used to handle end/home actions.
    `class` | `BasicTreeUI.TreeIncrementAction` TreeIncrementAction is used to handle up/down actions.
    `class` | `BasicTreeUI.TreeModelHandler` Forwards all TreeModel events to the TreeState.
    `class` | `BasicTreeUI.TreePageAction` TreePageAction handles page up and page down events.
    `class` | `BasicTreeUI.TreeSelectionHandler` Listens for changes in the selection model and updates the display accordingly.
    `class` | `BasicTreeUI.TreeToggleAction` For the first selected row expandedness will be toggled.
    `class` | `BasicTreeUI.TreeTraverseAction` `TreeTraverseAction` is the action used for left/right keys.

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected TreeCellEditor` | `cellEditor` Editor for the tree.
    `protected Icon` | `collapsedIcon`
    `protected boolean` | `createdCellEditor` Set to true if editor that is currently in the tree was created by this instance.
    `protected boolean` | `createdRenderer` Set to true if the renderer that is currently in the tree was created by this instance.
    `protected TreeCellRenderer` | `currentCellRenderer` Renderer that is being used to do the actual cell drawing.
    `protected int` | `depthOffset` How much the depth should be offset to properly calculate x locations.
    `protected Hashtable<TreePath,Boolean>` | `drawingCache` Used for minimizing the drawing of vertical lines.
    `protected Component` | `editingComponent` When editing, this will be the Component that is doing the actual editing.
    `protected TreePath` | `editingPath` Path that is being edited.
    `protected int` | `editingRow` Row that is being edited.
    `protected boolean` | `editorHasDifferentSize` Set to true if the editor has a different size than the renderer.
    `protected Icon` | `expandedIcon`
    `protected boolean` | `largeModel` True if doing optimizations for a largeModel.
    `protected int` | `lastSelectedRow` Index of the row that was last selected.
    `protected int` | `leftChildIndent` Distance between left margin and where vertical dashes will be drawn.
    `protected AbstractLayoutCache.NodeDimensions` | `nodeDimensions` Reponsible for telling the TreeState the size needed for a node.
    `protected Dimension` | `preferredMinSize` Minimum preferred size.
    `protected Dimension` | `preferredSize` Size needed to completely display all the nodes.
    `protected CellRendererPane` | `rendererPane` Used to paint the TreeCellRenderer.
    `protected int` | `rightChildIndent` Distance to add to leftChildIndent to determine where cell contents will be drawn.
    `protected boolean` | `stopEditingInCompleteEditing` Set to false when editing and shouldSelectCell() returns true meaning the node should be selected before editing, used in completeEditing.
    `protected int` | `totalChildIndent` Total distance that will be indented.
    `protected JTree` | `tree` Component that we're going to be drawing into.
    `protected TreeModel` | `treeModel` Used to determine what to display.
    `protected TreeSelectionModel` | `treeSelectionModel` Model maintaining the selection.
    `protected AbstractLayoutCache` | `treeState` Object responsible for handling sizing and expanded issues.
    `protected boolean` | `validCachedPreferredSize` Is the preferredSize valid?

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `BasicTreeUI()`

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `cancelEditing(JTree tree)` Cancels the current editing session.
    `protected void` | `checkForClickInExpandControl(TreePath path, int mouseX, int mouseY)` If the `mouseX` and `mouseY` are in the expand/collapse region of the `row`, this will toggle the row.
    `protected void` | `completeEditing()` Messages to stop the editing session.
    `protected void` | `completeEditing(boolean messageStop, boolean messageCancel, boolean messageTree)` Stops the editing session.
    `protected void` | `completeUIInstall()` Invoked from installUI after all the defaults/listeners have been installed.
    `protected void` | `completeUIUninstall()`
    `protected void` | `configureLayoutCache()` Resets the TreeState instance based on the tree we're providing the look and feel for.
    `protected CellEditorListener` | `createCellEditorListener()` Creates a listener to handle events from the current editor.
    `protected CellRendererPane` | `createCellRendererPane()` Returns the renderer pane that renderer components are placed in.
    `protected ComponentListener` | `createComponentListener()` Creates and returns a new ComponentHandler.
    `protected TreeCellEditor` | `createDefaultCellEditor()` Creates a default cell editor.
    `protected TreeCellRenderer` | `createDefaultCellRenderer()` Returns the default cell renderer that is used to do the stamping of each node.
    `protected FocusListener` | `createFocusListener()` Creates a listener that is responsible for updating the display when focus is lost/gained.
    `protected KeyListener` | `createKeyListener()` Creates the listener reponsible for getting key events from the tree.
    `protected AbstractLayoutCache` | `createLayoutCache()` Creates the object responsible for managing what is expanded, as well as the size of nodes.
    `protected MouseListener` | `createMouseListener()` Creates the listener responsible for updating the selection based on mouse events.
    `protected AbstractLayoutCache.NodeDimensions` | `createNodeDimensions()` Creates an instance of NodeDimensions that is able to determine the size of a given node in the tree.
    `protected PropertyChangeListener` | `createPropertyChangeListener()` Creates a listener that is responsible that updates the UI based on how the tree changes.
    `protected PropertyChangeListener` | `createSelectionModelPropertyChangeListener()` Creates the listener responsible for getting property change events from the selection model.
    `protected TreeExpansionListener` | `createTreeExpansionListener()` Creates and returns the object responsible for updating the treestate when nodes expanded state changes.
    `protected TreeModelListener` | `createTreeModelListener()` Returns a listener that can update the tree when the model changes.
    `protected TreeSelectionListener` | `createTreeSelectionListener()` Creates the listener that updates the display based on selection change methods.
    `static ComponentUI` | `createUI(JComponent x)`
    `protected void` | `drawCentered(Component c, Graphics graphics, Icon icon, int x, int y)`
    `protected void` | `drawDashedHorizontalLine(Graphics g, int y, int x1, int x2)`
    `protected void` | `drawDashedVerticalLine(Graphics g, int x, int y1, int y2)`
    `protected void` | `ensureRowsAreVisible(int beginRow, int endRow)` Ensures that the rows identified by beginRow through endRow are visible.
    `int` | `getBaseline(JComponent c, int width, int height)` Returns the baseline.
    `Component.BaselineResizeBehavior` | `getBaselineResizeBehavior(JComponent c)` Returns an enum indicating how the baseline of the component changes as the size changes.
    `protected TreeCellEditor` | `getCellEditor()`
    `protected TreeCellRenderer` | `getCellRenderer()` Return currentCellRenderer, which will either be the trees renderer, or defaultCellRenderer, which ever wasn't null.
    `TreePath` | `getClosestPathForLocation(JTree tree, int x, int y)` Returns the path to the node that is closest to x,y.
    `Icon` | `getCollapsedIcon()`
    `protected Rectangle` | `getDropLineRect(JTree.DropLocation loc)` Returns a unbounding box for the drop line.
    `TreePath` | `getEditingPath(JTree tree)` Returns the path to the element that is being edited.
    `Icon` | `getExpandedIcon()`
    `protected Color` | `getHashColor()`
    `protected int` | `getHorizontalLegBuffer()` The horizontal element of legs between nodes starts at the right of the left-hand side of the child node by default.
    `protected TreePath` | `getLastChildPath(TreePath parent)` Returns a path to the last child of `parent`.
    `protected int` | `getLeadSelectionRow()` Returns the lead row of the selection.
    `int` | `getLeftChildIndent()`
    `Dimension` | `getMaximumSize(JComponent c)` Returns the maximum size for this component, which will be the preferred size if the instance is currently in a JTree, or 0, 0.
    `Dimension` | `getMinimumSize(JComponent c)` Returns the minimum size for this component.
    `protected TreeModel` | `getModel()`
    `Rectangle` | `getPathBounds(JTree tree, TreePath path)` Returns the Rectangle enclosing the label portion that the last item in path will be drawn into.
    `TreePath` | `getPathForRow(JTree tree, int row)` Returns the path for passed in row.
    `Dimension` | `getPreferredMinSize()` Returns the minimum preferred size.
    `Dimension` | `getPreferredSize(JComponent c)` Returns the preferred size to properly display the tree, this is a cover method for getPreferredSize(c, true).
    `Dimension` | `getPreferredSize(JComponent c, boolean checkConsistency)` Returns the preferred size to represent the tree in c.
    `int` | `getRightChildIndent()`
    `int` | `getRowCount(JTree tree)` Returns the number of rows that are being displayed.
    `int` | `getRowForPath(JTree tree, TreePath path)` Returns the row that the last item identified in path is visible at.
    `protected int` | `getRowHeight()`
    `protected int` | `getRowX(int row, int depth)` Returns the location, along the x-axis, to render a particular row at.
    `protected TreeSelectionModel` | `getSelectionModel()`
    `protected boolean` | `getShowsRootHandles()`
    `protected int` | `getVerticalLegBuffer()` The vertical element of legs between nodes starts at the bottom of the parent node by default.
    `protected void` | `handleExpandControlClick(TreePath path, int mouseX, int mouseY)` Messaged when the user clicks the particular row, this invokes toggleExpandState.
    `protected void` | `installComponents()` Intalls the subcomponents of the tree, which is the renderer pane.
    `protected void` | `installDefaults()`
    `protected void` | `installKeyboardActions()`
    `protected void` | `installListeners()`
    `void` | `installUI(JComponent c)` Configures the specified component appropriately for the look and feel.
    `protected boolean` | `isDropLine(JTree.DropLocation loc)` Tells if a `DropLocation` should be indicated by a line between nodes.
    `protected boolean` | `isEditable()`
    `boolean` | `isEditing(JTree tree)` Returns true if the tree is being edited.
    `protected boolean` | `isLargeModel()`
    `protected boolean` | `isLeaf(int row)`
    `protected boolean` | `isLocationInExpandControl(TreePath path, int mouseX, int mouseY)` Returns true if `mouseX` and `mouseY` fall in the area of row that is used to expand/collapse the node and the node at `row` does not represent a leaf.
    `protected boolean` | `isMultiSelectEvent(MouseEvent event)` Returning true signifies a mouse event on the node should select from the anchor point.
    `protected boolean` | `isRootVisible()`
    `protected boolean` | `isToggleEvent(MouseEvent event)` Returning true indicates the row under the mouse should be toggled based on the event.
    `protected boolean` | `isToggleSelectionEvent(MouseEvent event)` Returning true signifies a mouse event on the node should toggle the selection of only the row under mouse.
    `void` | `paint(Graphics g, JComponent c)` Paints the specified component appropriately for the look and feel.
    `protected void` | `paintDropLine(Graphics g)` Paints the drop line.
    `protected void` | `paintExpandControl(Graphics g, Rectangle clipBounds, Insets insets, Rectangle bounds, TreePath path, int row, boolean isExpanded, boolean hasBeenExpanded, boolean isLeaf)` Paints the expand (toggle) part of a row.
    `protected void` | `paintHorizontalLine(Graphics g, JComponent c, int y, int left, int right)` Paints a horizontal line.
    `protected void` | `paintHorizontalPartOfLeg(Graphics g, Rectangle clipBounds, Insets insets, Rectangle bounds, TreePath path, int row, boolean isExpanded, boolean hasBeenExpanded, boolean isLeaf)` Paints the horizontal part of the leg.
    `protected void` | `paintRow(Graphics g, Rectangle clipBounds, Insets insets, Rectangle bounds, TreePath path, int row, boolean isExpanded, boolean hasBeenExpanded, boolean isLeaf)` Paints the renderer part of a row.
    `protected void` | `paintVerticalLine(Graphics g, JComponent c, int x, int top, int bottom)` Paints a vertical line.
    `protected void` | `paintVerticalPartOfLeg(Graphics g, Rectangle clipBounds, Insets insets, TreePath path)` Paints the vertical part of the leg.
    `protected void` | `pathWasCollapsed(TreePath path)` Messaged from the VisibleTreeNode after it has collapsed.
    `protected void` | `pathWasExpanded(TreePath path)` Messaged from the VisibleTreeNode after it has been expanded.
    `protected void` | `prepareForUIInstall()` Invoked after the `tree` instance variable has been set, but before any defaults/listeners have been installed.
    `protected void` | `prepareForUIUninstall()`
    `protected void` | `selectPathForEvent(TreePath path, MouseEvent event)` Messaged to update the selection based on a MouseEvent over a particular row.
    `protected void` | `setCellEditor(TreeCellEditor editor)` Sets the cell editor.
    `protected void` | `setCellRenderer(TreeCellRenderer tcr)` Sets the TreeCellRenderer to `tcr`.
    `void` | `setCollapsedIcon(Icon newG)`
    `protected void` | `setEditable(boolean newValue)` Configures the receiver to allow, or not allow, editing.
    `void` | `setExpandedIcon(Icon newG)`
    `protected void` | `setHashColor(Color color)`
    `protected void` | `setLargeModel(boolean largeModel)` Updates the componentListener, if necessary.
    `void` | `setLeftChildIndent(int newAmount)`
    `protected void` | `setModel(TreeModel model)` Sets the TreeModel.
    `void` | `setPreferredMinSize(Dimension newSize)` Sets the preferred minimum size.
    `void` | `setRightChildIndent(int newAmount)`
    `protected void` | `setRootVisible(boolean newValue)` Sets the root to being visible.
    `protected void` | `setRowHeight(int rowHeight)` Sets the row height, this is forwarded to the treeState.
    `protected void` | `setSelectionModel(TreeSelectionModel newLSM)` Resets the selection model.
    `protected void` | `setShowsRootHandles(boolean newValue)` Determines whether the node handles are to be displayed.
    `protected boolean` | `shouldPaintExpandControl(TreePath path, int row, boolean isExpanded, boolean hasBeenExpanded, boolean isLeaf)` Returns true if the expand (toggle) control should be drawn for the specified row.
    `protected boolean` | `startEditing(TreePath path, MouseEvent event)` Will start editing for node if there is a cellEditor and shouldSelectCell returns true.
    `void` | `startEditingAtPath(JTree tree, TreePath path)` Selects the last item in path and tries to edit it.
    `boolean` | `stopEditing(JTree tree)` Stops the current editing session.
    `protected void` | `toggleExpandState(TreePath path)` Expands path if it is not expanded, or collapses row if it is expanded.
    `protected void` | `uninstallComponents()` Uninstalls the renderer pane.
    `protected void` | `uninstallDefaults()`
    `protected void` | `uninstallKeyboardActions()`
    `protected void` | `uninstallListeners()`
    `void` | `uninstallUI(JComponent c)` Reverses configuration which was done on the specified component during `installUI`.
    `protected void` | `updateCachedPreferredSize()` Updates the `preferredSize` instance variable, which is returned from `getPreferredSize()`.
    `protected void` | `updateCellEditor()` Updates the cellEditor based on the editability of the JTree that we're contained in.
    `protected void` | `updateDepthOffset()` Updates how much each depth should be offset by.
    `protected void` | `updateExpandedDescendants(TreePath path)` Updates the expanded state of all the descendants of `path` by getting the expanded descendants from the tree and forwarding to the tree state.
    `protected void` | `updateLayoutCacheExpandedNodes()` Makes all the nodes that are expanded in JTree expanded in LayoutCache.
    `protected void` | `updateLeadSelectionRow()` Updates the lead row of the selection.
    `protected void` | `updateRenderer()` Messaged from the tree we're in when the renderer has changed.
    `protected void` | `updateSize()` Marks the cached size as being invalid, and messages the tree with `treeDidChange`.

    - ### Methods inherited from class javax.swing.plaf.ComponentUI

      `contains, getAccessibleChild, getAccessibleChildrenCount, update`

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

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

- - ### Field Detail

    - #### collapsedIcon

          protected transient Icon collapsedIcon

    - #### expandedIcon

          protected transient Icon expandedIcon

    - #### leftChildIndent

          protected int leftChildIndent

      Distance between left margin and where vertical dashes will be drawn.

    - #### rightChildIndent

          protected int rightChildIndent

      Distance to add to leftChildIndent to determine where cell contents will be drawn.

    - #### totalChildIndent

          protected int totalChildIndent

      Total distance that will be indented. The sum of leftChildIndent and rightChildIndent.

    - #### preferredMinSize

          protected Dimension preferredMinSize

      Minimum preferred size.

    - #### lastSelectedRow

          protected int lastSelectedRow

      Index of the row that was last selected.

    - #### tree

          protected JTree tree

      Component that we're going to be drawing into.

    - #### currentCellRenderer

          protected transient TreeCellRenderer currentCellRenderer

      Renderer that is being used to do the actual cell drawing.

    - #### createdRenderer

          protected boolean createdRenderer

      Set to true if the renderer that is currently in the tree was created by this instance.

    - #### cellEditor

          protected transient TreeCellEditor cellEditor

      Editor for the tree.

    - #### createdCellEditor

          protected boolean createdCellEditor

      Set to true if editor that is currently in the tree was created by this instance.

    - #### stopEditingInCompleteEditing

          protected boolean stopEditingInCompleteEditing

      Set to false when editing and shouldSelectCell() returns true meaning the node should be selected before editing, used in completeEditing.

    - #### rendererPane

          protected CellRendererPane rendererPane

      Used to paint the TreeCellRenderer.

    - #### preferredSize

          protected Dimension preferredSize

      Size needed to completely display all the nodes.

    - #### validCachedPreferredSize

          protected boolean validCachedPreferredSize

      Is the preferredSize valid?

    - #### treeState

          protected AbstractLayoutCache treeState

      Object responsible for handling sizing and expanded issues.

    - #### drawingCache

          protected Hashtable<TreePath,Boolean> drawingCache

      Used for minimizing the drawing of vertical lines.

    - #### largeModel

          protected boolean largeModel

      True if doing optimizations for a largeModel. Subclasses that don't support this may wish to override createLayoutCache to not return a FixedHeightLayoutCache instance.

    - #### nodeDimensions

          protected AbstractLayoutCache.NodeDimensions nodeDimensions

      Reponsible for telling the TreeState the size needed for a node.

    - #### treeModel

          protected TreeModel treeModel

      Used to determine what to display.

    - #### treeSelectionModel

          protected TreeSelectionModel treeSelectionModel

      Model maintaining the selection.

    - #### depthOffset

          protected int depthOffset

      How much the depth should be offset to properly calculate x locations. This is based on whether or not the root is visible, and if the root handles are visible.

    - #### editingComponent

          protected Component editingComponent

      When editing, this will be the Component that is doing the actual editing.

    - #### editingPath

          protected TreePath editingPath

      Path that is being edited.

    - #### editingRow

          protected int editingRow

      Row that is being edited. Should only be referenced if editingComponent is not null.

    - #### editorHasDifferentSize

          protected boolean editorHasDifferentSize

      Set to true if the editor has a different size than the renderer.

  - ### Constructor Detail

    - #### BasicTreeUI

          public BasicTreeUI()

  - ### Method Detail

    - #### createUI

          public static ComponentUI createUI(JComponent x)

    - #### getHashColor

          protected Color getHashColor()

    - #### setHashColor

          protected void setHashColor(Color color)

    - #### setLeftChildIndent

          public void setLeftChildIndent(int newAmount)

    - #### getLeftChildIndent

          public int getLeftChildIndent()

    - #### setRightChildIndent

          public void setRightChildIndent(int newAmount)

    - #### getRightChildIndent

          public int getRightChildIndent()

    - #### setExpandedIcon

          public void setExpandedIcon(Icon newG)

    - #### getExpandedIcon

          public Icon getExpandedIcon()

    - #### setCollapsedIcon

          public void setCollapsedIcon(Icon newG)

    - #### getCollapsedIcon

          public Icon getCollapsedIcon()

    - #### setLargeModel

          protected void setLargeModel(boolean largeModel)

      Updates the componentListener, if necessary.

    - #### isLargeModel

          protected boolean isLargeModel()

    - #### setRowHeight

          protected void setRowHeight(int rowHeight)

      Sets the row height, this is forwarded to the treeState.

    - #### getRowHeight

          protected int getRowHeight()

    - #### setCellRenderer

          protected void setCellRenderer(TreeCellRenderer tcr)

      Sets the TreeCellRenderer to `tcr`. This invokes `updateRenderer`.

    - #### getCellRenderer

          protected TreeCellRenderer getCellRenderer()

      Return currentCellRenderer, which will either be the trees renderer, or defaultCellRenderer, which ever wasn't null.

    - #### setModel

          protected void setModel(TreeModel model)

      Sets the TreeModel.

    - #### getModel

          protected TreeModel getModel()

    - #### setRootVisible

          protected void setRootVisible(boolean newValue)

      Sets the root to being visible.

    - #### isRootVisible

          protected boolean isRootVisible()

    - #### setShowsRootHandles

          protected void setShowsRootHandles(boolean newValue)

      Determines whether the node handles are to be displayed.

    - #### getShowsRootHandles

          protected boolean getShowsRootHandles()

    - #### setCellEditor

          protected void setCellEditor(TreeCellEditor editor)

      Sets the cell editor.

    - #### getCellEditor

          protected TreeCellEditor getCellEditor()

    - #### setEditable

          protected void setEditable(boolean newValue)

      Configures the receiver to allow, or not allow, editing.

    - #### isEditable

          protected boolean isEditable()

    - #### setSelectionModel

          protected void setSelectionModel(TreeSelectionModel newLSM)

      Resets the selection model. The appropriate listener are installed on the model.

    - #### getSelectionModel

          protected TreeSelectionModel getSelectionModel()

    - #### getPathBounds

          public Rectangle getPathBounds(JTree tree,
                                         TreePath path)

      Returns the Rectangle enclosing the label portion that the last item in path will be drawn into. Will return null if any component in path is currently valid.
      Specified by:
        `getPathBounds` in class `TreeUI`

    - #### getPathForRow

          public TreePath getPathForRow(JTree tree,
                                        int row)

      Returns the path for passed in row. If row is not visible null is returned.
      Specified by:
        `getPathForRow` in class `TreeUI`

    - #### getRowForPath

          public int getRowForPath(JTree tree,
                                   TreePath path)

      Returns the row that the last item identified in path is visible at. Will return -1 if any of the elements in path are not currently visible.
      Specified by:
        `getRowForPath` in class `TreeUI`

    - #### getRowCount

          public int getRowCount(JTree tree)

      Returns the number of rows that are being displayed.
      Specified by:
        `getRowCount` in class `TreeUI`

    - #### getClosestPathForLocation

          public TreePath getClosestPathForLocation(JTree tree,
                                                    int x,
                                                    int y)

      Returns the path to the node that is closest to x,y. If there is nothing currently visible this will return null, otherwise it'll always return a valid path. If you need to test if the returned object is exactly at x, y you should get the bounds for the returned path and test x, y against that.
      Specified by:
        `getClosestPathForLocation` in class `TreeUI`

    - #### isEditing

          public boolean isEditing(JTree tree)

      Returns true if the tree is being edited. The item that is being edited can be returned by getEditingPath().
      Specified by:
        `isEditing` in class `TreeUI`

    - #### stopEditing

          public boolean stopEditing(JTree tree)

      Stops the current editing session. This has no effect if the tree isn't being edited. Returns true if the editor allows the editing session to stop.
      Specified by:
        `stopEditing` in class `TreeUI`

    - #### cancelEditing

          public void cancelEditing(JTree tree)

      Cancels the current editing session.
      Specified by:
        `cancelEditing` in class `TreeUI`

    - #### startEditingAtPath

          public void startEditingAtPath(JTree tree,
                                         TreePath path)

      Selects the last item in path and tries to edit it. Editing will fail if the CellEditor won't allow it for the selected item.
      Specified by:
        `startEditingAtPath` in class `TreeUI`

    - #### getEditingPath

          public TreePath getEditingPath(JTree tree)

      Returns the path to the element that is being edited.
      Specified by:
        `getEditingPath` in class `TreeUI`

    - #### installUI

          public void installUI(JComponent c)

      Description copied from class: `ComponentUI`
      Configures the specified component appropriately for the look and feel. This method is invoked when the `ComponentUI` instance is being installed as the UI delegate on the specified component. This method should completely configure the component for the look and feel, including the following:
      1. Install default property values for color, fonts, borders, icons, opacity, etc. on the component. Whenever possible, property values initialized by the client program should not be overridden.
      2. Install a `LayoutManager` on the component if necessary.
      3. Create/add any required sub-components to the component.
      4. Create/install event listeners on the component.
      5. Create/install a `PropertyChangeListener` on the component in order to detect and respond to component property changes appropriately.
      6. Install keyboard UI (mnemonics, traversal, etc.) on the component.
      7. Initialize any appropriate instance data.
      Overrides:
        `installUI` in class `ComponentUI`
      Parameters:
        `c` - the component where this UI delegate is being installed
      See Also:
        `ComponentUI.uninstallUI(javax.swing.JComponent)`, `JComponent.setUI(javax.swing.plaf.ComponentUI)`, `JComponent.updateUI()`

    - #### prepareForUIInstall

          protected void prepareForUIInstall()

      Invoked after the `tree` instance variable has been set, but before any defaults/listeners have been installed.

    - #### completeUIInstall

          protected void completeUIInstall()

      Invoked from installUI after all the defaults/listeners have been installed.

    - #### installDefaults

          protected void installDefaults()

    - #### installListeners

          protected void installListeners()

    - #### installKeyboardActions

          protected void installKeyboardActions()

    - #### installComponents

          protected void installComponents()

      Intalls the subcomponents of the tree, which is the renderer pane.

    - #### createNodeDimensions

          protected AbstractLayoutCache.NodeDimensions createNodeDimensions()

      Creates an instance of NodeDimensions that is able to determine the size of a given node in the tree.

    - #### createPropertyChangeListener

          protected PropertyChangeListener createPropertyChangeListener()

      Creates a listener that is responsible that updates the UI based on how the tree changes.

    - #### createMouseListener

          protected MouseListener createMouseListener()

      Creates the listener responsible for updating the selection based on mouse events.

    - #### createFocusListener

          protected FocusListener createFocusListener()

      Creates a listener that is responsible for updating the display when focus is lost/gained.

    - #### createKeyListener

          protected KeyListener createKeyListener()

      Creates the listener reponsible for getting key events from the tree.

    - #### createSelectionModelPropertyChangeListener

          protected PropertyChangeListener createSelectionModelPropertyChangeListener()

      Creates the listener responsible for getting property change events from the selection model.

    - #### createTreeSelectionListener

          protected TreeSelectionListener createTreeSelectionListener()

      Creates the listener that updates the display based on selection change methods.

    - #### createCellEditorListener

          protected CellEditorListener createCellEditorListener()

      Creates a listener to handle events from the current editor.

    - #### createComponentListener

          protected ComponentListener createComponentListener()

      Creates and returns a new ComponentHandler. This is used for the large model to mark the validCachedPreferredSize as invalid when the component moves.

    - #### createTreeExpansionListener

          protected TreeExpansionListener createTreeExpansionListener()

      Creates and returns the object responsible for updating the treestate when nodes expanded state changes.

    - #### createLayoutCache

          protected AbstractLayoutCache createLayoutCache()

      Creates the object responsible for managing what is expanded, as well as the size of nodes.

    - #### createCellRendererPane

          protected CellRendererPane createCellRendererPane()

      Returns the renderer pane that renderer components are placed in.

    - #### createDefaultCellEditor

          protected TreeCellEditor createDefaultCellEditor()

      Creates a default cell editor.

    - #### createDefaultCellRenderer

          protected TreeCellRenderer createDefaultCellRenderer()

      Returns the default cell renderer that is used to do the stamping of each node.

    - #### createTreeModelListener

          protected TreeModelListener createTreeModelListener()

      Returns a listener that can update the tree when the model changes.

    - #### uninstallUI

          public void uninstallUI(JComponent c)

      Description copied from class: `ComponentUI`
      Reverses configuration which was done on the specified component during `installUI`. This method is invoked when this `UIComponent` instance is being removed as the UI delegate for the specified component. This method should undo the configuration performed in `installUI`, being careful to leave the `JComponent` instance in a clean state (no extraneous listeners, look-and-feel-specific property objects, etc.). This should include the following:
      1. Remove any UI-set borders from the component.
      2. Remove any UI-set layout managers on the component.
      3. Remove any UI-added sub-components from the component.
      4. Remove any UI-added event/property listeners from the component.
      5. Remove any UI-installed keyboard UI from the component.
      6. Nullify any allocated instance data objects to allow for GC.
      Overrides:
        `uninstallUI` in class `ComponentUI`
      Parameters:
        `c` - the component from which this UI delegate is being removed; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components
      See Also:
        `ComponentUI.installUI(javax.swing.JComponent)`, `JComponent.updateUI()`

    - #### prepareForUIUninstall

          protected void prepareForUIUninstall()

    - #### completeUIUninstall

          protected void completeUIUninstall()

    - #### uninstallDefaults

          protected void uninstallDefaults()

    - #### uninstallListeners

          protected void uninstallListeners()

    - #### uninstallKeyboardActions

          protected void uninstallKeyboardActions()

    - #### uninstallComponents

          protected void uninstallComponents()

      Uninstalls the renderer pane.

    - #### getBaseline

          public int getBaseline(JComponent c,
                                 int width,
                                 int height)

      Returns the baseline.
      Overrides:
        `getBaseline` in class `ComponentUI`
      Parameters:
        `c` - `JComponent` baseline is being requested for
        `width` - the width to get the baseline for
        `height` - the height to get the baseline for
      Returns:
        baseline or a value < 0 indicating there is no reasonable baseline
      Throws:
        `NullPointerException` - if `c` is `null`
        `IllegalArgumentException` - if width or height is < 0
      Since:
        1.6
      See Also:
        `JComponent.getBaseline(int, int)`

    - #### getBaselineResizeBehavior

          public Component.BaselineResizeBehavior getBaselineResizeBehavior(JComponent c)

      Returns an enum indicating how the baseline of the component changes as the size changes.
      Overrides:
        `getBaselineResizeBehavior` in class `ComponentUI`
      Parameters:
        `c` - `JComponent` to return baseline resize behavior for
      Returns:
        an enum indicating how the baseline changes as the component size changes
      Throws:
        `NullPointerException` - if `c` is `null`
      Since:
        1.6
      See Also:
        `JComponent.getBaseline(int, int)`

    - #### paint

          public void paint(Graphics g,
                            JComponent c)

      Description copied from class: `ComponentUI`
      Paints the specified component appropriately for the look and feel. This method is invoked from the `ComponentUI.update` method when the specified component is being painted. Subclasses should override this method and use the specified `Graphics` object to render the content of the component.
      Overrides:
        `paint` in class `ComponentUI`
      Parameters:
        `g` - the `Graphics` context in which to paint
        `c` - the component being painted; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components
      See Also:
        `ComponentUI.update(java.awt.Graphics, javax.swing.JComponent)`

    - #### isDropLine

          protected boolean isDropLine(JTree.DropLocation loc)

      Tells if a `DropLocation` should be indicated by a line between nodes. This is meant for `javax.swing.DropMode.INSERT` and `javax.swing.DropMode.ON_OR_INSERT` drop modes.
      Parameters:
        `loc` - a `DropLocation`
      Returns:
        `true` if the drop location should be shown as a line
      Since:
        1.7

    - #### paintDropLine

          protected void paintDropLine(Graphics g)

      Paints the drop line.
      Parameters:
        `g` - `Graphics` object to draw on
      Since:
        1.7

    - #### getDropLineRect

          protected Rectangle getDropLineRect(JTree.DropLocation loc)

      Returns a unbounding box for the drop line.
      Parameters:
        `loc` - a `DropLocation`
      Returns:
        bounding box for the drop line
      Since:
        1.7

    - #### paintHorizontalPartOfLeg

          protected void paintHorizontalPartOfLeg(Graphics g,
                                                  Rectangle clipBounds,
                                                  Insets insets,
                                                  Rectangle bounds,
                                                  TreePath path,
                                                  int row,
                                                  boolean isExpanded,
                                                  boolean hasBeenExpanded,
                                                  boolean isLeaf)

      Paints the horizontal part of the leg. The receiver should NOT modify `clipBounds`, or `insets`.

      NOTE: `parentRow` can be -1 if the root is not visible.

    - #### paintVerticalPartOfLeg

          protected void paintVerticalPartOfLeg(Graphics g,
                                                Rectangle clipBounds,
                                                Insets insets,
                                                TreePath path)

      Paints the vertical part of the leg. The receiver should NOT modify `clipBounds`, `insets`.

    - #### paintExpandControl

          protected void paintExpandControl(Graphics g,
                                            Rectangle clipBounds,
                                            Insets insets,
                                            Rectangle bounds,
                                            TreePath path,
                                            int row,
                                            boolean isExpanded,
                                            boolean hasBeenExpanded,
                                            boolean isLeaf)

      Paints the expand (toggle) part of a row. The receiver should NOT modify `clipBounds`, or `insets`.

    - #### paintRow

          protected void paintRow(Graphics g,
                                  Rectangle clipBounds,
                                  Insets insets,
                                  Rectangle bounds,
                                  TreePath path,
                                  int row,
                                  boolean isExpanded,
                                  boolean hasBeenExpanded,
                                  boolean isLeaf)

      Paints the renderer part of a row. The receiver should NOT modify `clipBounds`, or `insets`.

    - #### shouldPaintExpandControl

          protected boolean shouldPaintExpandControl(TreePath path,
                                                     int row,
                                                     boolean isExpanded,
                                                     boolean hasBeenExpanded,
                                                     boolean isLeaf)

      Returns true if the expand (toggle) control should be drawn for the specified row.

    - #### paintVerticalLine

          protected void paintVerticalLine(Graphics g,
                                           JComponent c,
                                           int x,
                                           int top,
                                           int bottom)

      Paints a vertical line.

    - #### paintHorizontalLine

          protected void paintHorizontalLine(Graphics g,
                                             JComponent c,
                                             int y,
                                             int left,
                                             int right)

      Paints a horizontal line.

    - #### getVerticalLegBuffer

          protected int getVerticalLegBuffer()

      The vertical element of legs between nodes starts at the bottom of the parent node by default. This method makes the leg start below that.

    - #### getHorizontalLegBuffer

          protected int getHorizontalLegBuffer()

      The horizontal element of legs between nodes starts at the right of the left-hand side of the child node by default. This method makes the leg end before that.

    - #### drawCentered

          protected void drawCentered(Component c,
                                      Graphics graphics,
                                      Icon icon,
                                      int x,
                                      int y)

    - #### drawDashedHorizontalLine

          protected void drawDashedHorizontalLine(Graphics g,
                                                  int y,
                                                  int x1,
                                                  int x2)

    - #### drawDashedVerticalLine

          protected void drawDashedVerticalLine(Graphics g,
                                                int x,
                                                int y1,
                                                int y2)

    - #### getRowX

          protected int getRowX(int row,
                                int depth)

      Returns the location, along the x-axis, to render a particular row at. The return value does not include any Insets specified on the JTree. This does not check for the validity of the row or depth, it is assumed to be correct and will not throw an Exception if the row or depth doesn't match that of the tree.
      Parameters:
        `row` - Row to return x location for
        `depth` - Depth of the row
      Returns:
        amount to indent the given row.
      Since:
        1.5

    - #### updateLayoutCacheExpandedNodes

          protected void updateLayoutCacheExpandedNodes()

      Makes all the nodes that are expanded in JTree expanded in LayoutCache. This invokes updateExpandedDescendants with the root path.

    - #### updateExpandedDescendants

          protected void updateExpandedDescendants(TreePath path)

      Updates the expanded state of all the descendants of `path` by getting the expanded descendants from the tree and forwarding to the tree state.

    - #### getLastChildPath

          protected TreePath getLastChildPath(TreePath parent)

      Returns a path to the last child of `parent`.

    - #### updateDepthOffset

          protected void updateDepthOffset()

      Updates how much each depth should be offset by.

    - #### updateCellEditor

          protected void updateCellEditor()

      Updates the cellEditor based on the editability of the JTree that we're contained in. If the tree is editable but doesn't have a cellEditor, a basic one will be used.

    - #### updateRenderer

          protected void updateRenderer()

      Messaged from the tree we're in when the renderer has changed.

    - #### configureLayoutCache

          protected void configureLayoutCache()

      Resets the TreeState instance based on the tree we're providing the look and feel for.

    - #### updateSize

          protected void updateSize()

      Marks the cached size as being invalid, and messages the tree with `treeDidChange`.

    - #### updateCachedPreferredSize

          protected void updateCachedPreferredSize()

      Updates the `preferredSize` instance variable, which is returned from `getPreferredSize()`.

      For left to right orientations, the size is determined from the current AbstractLayoutCache. For RTL orientations, the preferred size becomes the width minus the minimum x position.

    - #### pathWasExpanded

          protected void pathWasExpanded(TreePath path)

      Messaged from the VisibleTreeNode after it has been expanded.

    - #### pathWasCollapsed

          protected void pathWasCollapsed(TreePath path)

      Messaged from the VisibleTreeNode after it has collapsed.

    - #### ensureRowsAreVisible

          protected void ensureRowsAreVisible(int beginRow,
                                              int endRow)

      Ensures that the rows identified by beginRow through endRow are visible.

    - #### setPreferredMinSize

          public void setPreferredMinSize(Dimension newSize)

      Sets the preferred minimum size.

    - #### getPreferredMinSize

          public Dimension getPreferredMinSize()

      Returns the minimum preferred size.

    - #### getPreferredSize

          public Dimension getPreferredSize(JComponent c)

      Returns the preferred size to properly display the tree, this is a cover method for getPreferredSize(c, true).
      Overrides:
        `getPreferredSize` in class `ComponentUI`
      Parameters:
        `c` - the component whose preferred size is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components
      See Also:
        `JComponent.getPreferredSize()`, `LayoutManager.preferredLayoutSize(java.awt.Container)`

    - #### getPreferredSize

          public Dimension getPreferredSize(JComponent c,
                                            boolean checkConsistency)

      Returns the preferred size to represent the tree in c. If checkConsistency is true checkConsistency is messaged first.

    - #### getMinimumSize

          public Dimension getMinimumSize(JComponent c)

      Returns the minimum size for this component. Which will be the min preferred size or 0, 0.
      Overrides:
        `getMinimumSize` in class `ComponentUI`
      Parameters:
        `c` - the component whose minimum size is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components
      Returns:
        a `Dimension` object or `null`
      See Also:
        `JComponent.getMinimumSize()`, `LayoutManager.minimumLayoutSize(java.awt.Container)`, `ComponentUI.getPreferredSize(javax.swing.JComponent)`

    - #### getMaximumSize

          public Dimension getMaximumSize(JComponent c)

      Returns the maximum size for this component, which will be the preferred size if the instance is currently in a JTree, or 0, 0.
      Overrides:
        `getMaximumSize` in class `ComponentUI`
      Parameters:
        `c` - the component whose maximum size is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components
      Returns:
        a `Dimension` object or `null`
      See Also:
        `JComponent.getMaximumSize()`, `LayoutManager2.maximumLayoutSize(java.awt.Container)`

    - #### completeEditing

          protected void completeEditing()

      Messages to stop the editing session. If the UI the receiver is providing the look and feel for returns true from `getInvokesStopCellEditing`, stopCellEditing will invoked on the current editor. Then completeEditing will be messaged with false, true, false to cancel any lingering editing.

    - #### completeEditing

          protected void completeEditing(boolean messageStop,
                                         boolean messageCancel,
                                         boolean messageTree)

      Stops the editing session. If messageStop is true the editor is messaged with stopEditing, if messageCancel is true the editor is messaged with cancelEditing. If messageTree is true the treeModel is messaged with valueForPathChanged.

    - #### startEditing

          protected boolean startEditing(TreePath path,
                                         MouseEvent event)

      Will start editing for node if there is a cellEditor and shouldSelectCell returns true.

      This assumes that path is valid and visible.

    - #### checkForClickInExpandControl

          protected void checkForClickInExpandControl(TreePath path,
                                                      int mouseX,
                                                      int mouseY)

      If the `mouseX` and `mouseY` are in the expand/collapse region of the `row`, this will toggle the row.

    - #### isLocationInExpandControl

          protected boolean isLocationInExpandControl(TreePath path,
                                                      int mouseX,
                                                      int mouseY)

      Returns true if `mouseX` and `mouseY` fall in the area of row that is used to expand/collapse the node and the node at `row` does not represent a leaf.

    - #### handleExpandControlClick

          protected void handleExpandControlClick(TreePath path,
                                                  int mouseX,
                                                  int mouseY)

      Messaged when the user clicks the particular row, this invokes toggleExpandState.

    - #### toggleExpandState

          protected void toggleExpandState(TreePath path)

      Expands path if it is not expanded, or collapses row if it is expanded. If expanding a path and JTree scrolls on expand, ensureRowsAreVisible is invoked to scroll as many of the children to visible as possible (tries to scroll to last visible descendant of path).

    - #### isToggleSelectionEvent

          protected boolean isToggleSelectionEvent(MouseEvent event)

      Returning true signifies a mouse event on the node should toggle the selection of only the row under mouse.

    - #### isMultiSelectEvent

          protected boolean isMultiSelectEvent(MouseEvent event)

      Returning true signifies a mouse event on the node should select from the anchor point.

    - #### isToggleEvent

          protected boolean isToggleEvent(MouseEvent event)

      Returning true indicates the row under the mouse should be toggled based on the event. This is invoked after checkForClickInExpandControl, implying the location is not in the expand (toggle) control

    - #### selectPathForEvent

          protected void selectPathForEvent(TreePath path,
                                            MouseEvent event)

      Messaged to update the selection based on a MouseEvent over a particular row. If the event is a toggle selection event, the row is either selected, or deselected. If the event identifies a multi selection event, the selection is updated from the anchor point. Otherwise the row is selected, and if the event specified a toggle event the row is expanded/collapsed.

    - #### isLeaf

          protected boolean isLeaf(int row)

      Returns:
        true if the node at `row` is a leaf.

    - #### updateLeadSelectionRow

          protected void updateLeadSelectionRow()

      Updates the lead row of the selection.
      Since:
        1.7

    - #### getLeadSelectionRow

          protected int getLeadSelectionRow()

      Returns the lead row of the selection.
      Returns:
        selection lead row
      Since:
        1.7

Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2026, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.