FixedHeightLayoutCache (Java Platform SE 8 )
Keywords: javax.swing.tree.FixedHeightLayoutCache class
Date: 2026-06-25

javax.swing.tree

## Class FixedHeightLayoutCache

- java.lang.Object
- - javax.swing.tree.AbstractLayoutCache
  - - javax.swing.tree.FixedHeightLayoutCache

- All Implemented Interfaces:
    RowMapper

      public class FixedHeightLayoutCache
      extends AbstractLayoutCache

  NOTE: This will become more open in a future release.

  Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans™ has been added to the `java.beans` package. Please see `XMLEncoder`.

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class javax.swing.tree.AbstractLayoutCache

      `AbstractLayoutCache.NodeDimensions`

  - ### Field Summary

    - ### Fields inherited from class javax.swing.tree.AbstractLayoutCache

      `nodeDimensions, rootVisible, rowHeight, treeModel, treeSelectionModel`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `FixedHeightLayoutCache()`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Rectangle` | `getBounds(TreePath path, Rectangle placeIn)` Returns a rectangle giving the bounds needed to draw path.
    `boolean` | `getExpandedState(TreePath path)` Returns true if the path is expanded, and visible.
    `TreePath` | `getPathClosestTo(int x, int y)` Returns the path to the node that is closest to x,y.
    `TreePath` | `getPathForRow(int row)` Returns the path for passed in row.
    `int` | `getRowCount()` Returns the number of visible rows.
    `int` | `getRowForPath(TreePath path)` Returns the row that the last item identified in path is visible at.
    `int` | `getVisibleChildCount(TreePath path)` Returns the number of visible children for row.
    `Enumeration<TreePath>` | `getVisiblePathsFrom(TreePath path)` Returns an Enumerator that increments over the visible paths starting at the passed in location.
    `void` | `invalidatePathBounds(TreePath path)` Does nothing, FixedHeightLayoutCache doesn't cache width, and that is all that could change.
    `void` | `invalidateSizes()` Informs the TreeState that it needs to recalculate all the sizes it is referencing.
    `boolean` | `isExpanded(TreePath path)` Returns true if the value identified by row is currently expanded.
    `void` | `setExpandedState(TreePath path, boolean isExpanded)` Marks the path `path` expanded state to `isExpanded`.
    `void` | `setModel(TreeModel newModel)` Sets the TreeModel that will provide the data.
    `void` | `setRootVisible(boolean rootVisible)` Determines whether or not the root node from the TreeModel is visible.
    `void` | `setRowHeight(int rowHeight)` Sets the height of each cell.
    `void` | `treeNodesChanged(TreeModelEvent e)` Invoked after a node (or a set of siblings) has changed in some way.
    `void` | `treeNodesInserted(TreeModelEvent e)` Invoked after nodes have been inserted into the tree.
    `void` | `treeNodesRemoved(TreeModelEvent e)` Invoked after nodes have been removed from the tree.
    `void` | `treeStructureChanged(TreeModelEvent e)` Invoked after the tree has drastically changed structure from a given node down.

    - ### Methods inherited from class javax.swing.tree.AbstractLayoutCache

      `getModel, getNodeDimensions, getNodeDimensions, getPreferredHeight, getPreferredWidth, getRowHeight, getRowsForPaths, getSelectionModel, isFixedRowHeight, isRootVisible, setNodeDimensions, setSelectionModel`

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

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

- - ### Constructor Detail

    - #### FixedHeightLayoutCache

          public FixedHeightLayoutCache()

  - ### Method Detail

    - #### setModel

          public void setModel(TreeModel newModel)

      Sets the TreeModel that will provide the data.
      Overrides:
        `setModel` in class `AbstractLayoutCache`
      Parameters:
        `newModel` - the TreeModel that is to provide the data

    - #### setRootVisible

          public void setRootVisible(boolean rootVisible)

      Determines whether or not the root node from the TreeModel is visible.
      Overrides:
        `setRootVisible` in class `AbstractLayoutCache`
      Parameters:
        `rootVisible` - true if the root node of the tree is to be displayed
      See Also:
        `AbstractLayoutCache.rootVisible`

    - #### setRowHeight

          public void setRowHeight(int rowHeight)

      Sets the height of each cell. If rowHeight is less than or equal to 0 this will throw an IllegalArgumentException.
      Overrides:
        `setRowHeight` in class `AbstractLayoutCache`
      Parameters:
        `rowHeight` - the height of each cell, in pixels

    - #### getRowCount

          public int getRowCount()

      Returns the number of visible rows.
      Specified by:
        `getRowCount` in class `AbstractLayoutCache`
      Returns:
        the number of rows being displayed

    - #### invalidatePathBounds

          public void invalidatePathBounds(TreePath path)

      Does nothing, FixedHeightLayoutCache doesn't cache width, and that is all that could change.
      Specified by:
        `invalidatePathBounds` in class `AbstractLayoutCache`
      Parameters:
        `path` - the path being updated

    - #### invalidateSizes

          public void invalidateSizes()

      Informs the TreeState that it needs to recalculate all the sizes it is referencing.
      Specified by:
        `invalidateSizes` in class `AbstractLayoutCache`

    - #### isExpanded

          public boolean isExpanded(TreePath path)

      Returns true if the value identified by row is currently expanded.
      Specified by:
        `isExpanded` in class `AbstractLayoutCache`

    - #### getBounds

          public Rectangle getBounds(TreePath path,
                                     Rectangle placeIn)

      Returns a rectangle giving the bounds needed to draw path.
      Specified by:
        `getBounds` in class `AbstractLayoutCache`
      Parameters:
        `path` - a TreePath specifying a node
        `placeIn` - a Rectangle object giving the available space
      Returns:
        a Rectangle object specifying the space to be used

    - #### getPathForRow

          public TreePath getPathForRow(int row)

      Returns the path for passed in row. If row is not visible null is returned.
      Specified by:
        `getPathForRow` in class `AbstractLayoutCache`
      Parameters:
        `row` - the row being queried
      Returns:
        the `TreePath` for the given row

    - #### getRowForPath

          public int getRowForPath(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 `AbstractLayoutCache`
      Parameters:
        `path` - the `TreePath` being queried
      Returns:
        the row where the last item in path is visible or -1 if any elements in path aren't currently visible

    - #### getPathClosestTo

          public TreePath getPathClosestTo(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:
        `getPathClosestTo` in class `AbstractLayoutCache`
      Parameters:
        `x` - the horizontal component of the desired location
        `y` - the vertical component of the desired location
      Returns:
        the `TreePath` closest to the specified point

    - #### getVisibleChildCount

          public int getVisibleChildCount(TreePath path)

      Returns the number of visible children for row.
      Specified by:
        `getVisibleChildCount` in class `AbstractLayoutCache`
      Parameters:
        `path` - the path being queried
      Returns:
        the number of visible children for the specified path

    - #### getVisiblePathsFrom

          public Enumeration<TreePath> getVisiblePathsFrom(TreePath path)

      Returns an Enumerator that increments over the visible paths starting at the passed in location. The ordering of the enumeration is based on how the paths are displayed.
      Specified by:
        `getVisiblePathsFrom` in class `AbstractLayoutCache`
      Parameters:
        `path` - the starting location for the enumeration
      Returns:
        the `Enumerator` starting at the desired location

    - #### setExpandedState

          public void setExpandedState(TreePath path,
                                       boolean isExpanded)

      Marks the path `path` expanded state to `isExpanded`.
      Specified by:
        `setExpandedState` in class `AbstractLayoutCache`
      Parameters:
        `path` - the path being expanded or collapsed
        `isExpanded` - true if the path should be expanded, false otherwise

    - #### getExpandedState

          public boolean getExpandedState(TreePath path)

      Returns true if the path is expanded, and visible.
      Specified by:
        `getExpandedState` in class `AbstractLayoutCache`
      Parameters:
        `path` - the path being queried
      Returns:
        true if the path is expanded and visible, false otherwise

    - #### treeNodesChanged

          public void treeNodesChanged(TreeModelEvent e)

      Invoked after a node (or a set of siblings) has changed in some way. The node(s) have not changed locations in the tree or altered their children arrays, but other attributes have changed and may affect presentation. Example: the name of a file has changed, but it is in the same location in the file system.

      e.path() returns the path the parent of the changed node(s).

      e.childIndices() returns the index(es) of the changed node(s).

      Specified by:
        `treeNodesChanged` in class `AbstractLayoutCache`
      Parameters:
        `e` - the `TreeModelEvent`

    - #### treeNodesInserted

          public void treeNodesInserted(TreeModelEvent e)

      Invoked after nodes have been inserted into the tree.

      e.path() returns the parent of the new nodes

      e.childIndices() returns the indices of the new nodes in ascending order.

      Specified by:
        `treeNodesInserted` in class `AbstractLayoutCache`
      Parameters:
        `e` - the `TreeModelEvent`

    - #### treeNodesRemoved

          public void treeNodesRemoved(TreeModelEvent e)

      Invoked after nodes have been removed from the tree. Note that if a subtree is removed from the tree, this method may only be invoked once for the root of the removed subtree, not once for each individual set of siblings removed.

      e.path() returns the former parent of the deleted nodes.

      e.childIndices() returns the indices the nodes had before they were deleted in ascending order.

      Specified by:
        `treeNodesRemoved` in class `AbstractLayoutCache`
      Parameters:
        `e` - the `TreeModelEvent`

    - #### treeStructureChanged

          public void treeStructureChanged(TreeModelEvent e)

      Invoked after the tree has drastically changed structure from a given node down. If the path returned by e.getPath() is of length one and the first element does not identify the current root node the first element should become the new root of the tree.

      e.path() holds the path to the node.

      e.childIndices() returns null.

      Specified by:
        `treeStructureChanged` in class `AbstractLayoutCache`
      Parameters:
        `e` - the `TreeModelEvent`

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