AbstractLayoutCache (Java Platform SE 8 )
Keywords: javax.swing.tree.AbstractLayoutCache class
Date: 2026-04-22

javax.swing.tree

## Class AbstractLayoutCache

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

- All Implemented Interfaces:
    RowMapper
  Direct Known Subclasses:
    FixedHeightLayoutCache, VariableHeightLayoutCache

      public abstract class AbstractLayoutCache
      extends Object
      implements RowMapper

  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
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `AbstractLayoutCache.NodeDimensions` Used by `AbstractLayoutCache` to determine the size and x origin of a particular node.

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected AbstractLayoutCache.NodeDimensions` | `nodeDimensions` Object responsible for getting the size of a node.
    `protected boolean` | `rootVisible` True if the root node is displayed, false if its children are the highest visible nodes.
    `protected int` | `rowHeight` Height to use for each row.
    `protected TreeModel` | `treeModel` Model providing information.
    `protected TreeSelectionModel` | `treeSelectionModel` Selection model.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `AbstractLayoutCache()`

  - ### Method Summary

    All Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `abstract Rectangle` | `getBounds(TreePath path, Rectangle placeIn)` Returns a rectangle giving the bounds needed to draw path.
    `abstract boolean` | `getExpandedState(TreePath path)` Returns true if the path is expanded, and visible.
    `TreeModel` | `getModel()` Returns the `TreeModel` that is providing the data.
    `AbstractLayoutCache.NodeDimensions` | `getNodeDimensions()` Returns the object that renders nodes in the tree, and which is responsible for calculating the dimensions of individual nodes.
    `protected Rectangle` | `getNodeDimensions(Object value, int row, int depth, boolean expanded, Rectangle placeIn)` Returns, by reference in `placeIn`, the size needed to represent `value`.
    `abstract TreePath` | `getPathClosestTo(int x, int y)` Returns the path to the node that is closest to x,y.
    `abstract TreePath` | `getPathForRow(int row)` Returns the path for passed in row.
    `int` | `getPreferredHeight()` Returns the preferred height.
    `int` | `getPreferredWidth(Rectangle bounds)` Returns the preferred width for the passed in region.
    `abstract int` | `getRowCount()` Number of rows being displayed.
    `abstract int` | `getRowForPath(TreePath path)` Returns the row that the last item identified in path is visible at.
    `int` | `getRowHeight()` Returns the height of each row.
    `int[]` | `getRowsForPaths(TreePath[] paths)` Returns the rows that the `TreePath` instances in `path` are being displayed at.
    `TreeSelectionModel` | `getSelectionModel()` Returns the model used to maintain the selection.
    `abstract int` | `getVisibleChildCount(TreePath path)` Returns the number of visible children for row.
    `abstract Enumeration<TreePath>` | `getVisiblePathsFrom(TreePath path)` Returns an `Enumerator` that increments over the visible paths starting at the passed in location.
    `abstract void` | `invalidatePathBounds(TreePath path)` Instructs the `LayoutCache` that the bounds for `path` are invalid, and need to be updated.
    `abstract void` | `invalidateSizes()` Informs the `TreeState` that it needs to recalculate all the sizes it is referencing.
    `abstract boolean` | `isExpanded(TreePath path)` Returns true if the value identified by row is currently expanded.
    `protected boolean` | `isFixedRowHeight()` Returns true if the height of each row is a fixed size.
    `boolean` | `isRootVisible()` Returns true if the root node of the tree is displayed.
    `abstract 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` | `setNodeDimensions(AbstractLayoutCache.NodeDimensions nd)` Sets the renderer that is responsible for drawing nodes in the tree and which is therefore responsible for calculating the dimensions of individual nodes.
    `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` | `setSelectionModel(TreeSelectionModel newLSM)` Sets the `TreeSelectionModel` used to manage the selection to new LSM.
    `abstract void` | `treeNodesChanged(TreeModelEvent e)` Invoked after a node (or a set of siblings) has changed in some way.
    `abstract void` | `treeNodesInserted(TreeModelEvent e)` Invoked after nodes have been inserted into the tree.
    `abstract void` | `treeNodesRemoved(TreeModelEvent e)` Invoked after nodes have been removed from the tree.
    `abstract void` | `treeStructureChanged(TreeModelEvent e)` Invoked after the tree has drastically changed structure from a given node down.

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

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

- - ### Field Detail

    - #### nodeDimensions

          protected AbstractLayoutCache.NodeDimensions nodeDimensions

      Object responsible for getting the size of a node.

    - #### treeModel

          protected TreeModel treeModel

      Model providing information.

    - #### treeSelectionModel

          protected TreeSelectionModel treeSelectionModel

      Selection model.

    - #### rootVisible

          protected boolean rootVisible

      True if the root node is displayed, false if its children are the highest visible nodes.

    - #### rowHeight

          protected int rowHeight

      Height to use for each row. If this is <= 0 the renderer will be used to determine the height for each row.

  - ### Constructor Detail

    - #### AbstractLayoutCache

          public AbstractLayoutCache()

  - ### Method Detail

    - #### setNodeDimensions

          public void setNodeDimensions(AbstractLayoutCache.NodeDimensions nd)

      Sets the renderer that is responsible for drawing nodes in the tree and which is therefore responsible for calculating the dimensions of individual nodes.
      Parameters:
        `nd` - a `NodeDimensions` object

    - #### getNodeDimensions

          public AbstractLayoutCache.NodeDimensions getNodeDimensions()

      Returns the object that renders nodes in the tree, and which is responsible for calculating the dimensions of individual nodes.
      Returns:
        the `NodeDimensions` object

    - #### setModel

          public void setModel(TreeModel newModel)

      Sets the `TreeModel` that will provide the data.
      Parameters:
        `newModel` - the `TreeModel` that is to provide the data

    - #### getModel

          public TreeModel getModel()

      Returns the `TreeModel` that is providing the data.
      Returns:
        the `TreeModel` that is providing the data

    - #### setRootVisible

          public void setRootVisible(boolean rootVisible)

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

    - #### isRootVisible

          public boolean isRootVisible()

      Returns true if the root node of the tree is displayed.
      Returns:
        true if the root node of the tree is displayed
      See Also:
        `rootVisible`

    - #### setRowHeight

          public void setRowHeight(int rowHeight)

      Sets the height of each cell. If the specified value is less than or equal to zero the current cell renderer is queried for each row's height.
      Parameters:
        `rowHeight` - the height of each cell, in pixels

    - #### getRowHeight

          public int getRowHeight()

      Returns the height of each row. If the returned value is less than or equal to 0 the height for each row is determined by the renderer.

    - #### setSelectionModel

          public void setSelectionModel(TreeSelectionModel newLSM)

      Sets the `TreeSelectionModel` used to manage the selection to new LSM.
      Parameters:
        `newLSM` - the new `TreeSelectionModel`

    - #### getSelectionModel

          public TreeSelectionModel getSelectionModel()

      Returns the model used to maintain the selection.
      Returns:
        the `treeSelectionModel`

    - #### getPreferredHeight

          public int getPreferredHeight()

      Returns the preferred height.
      Returns:
        the preferred height

    - #### getPreferredWidth

          public int getPreferredWidth(Rectangle bounds)

      Returns the preferred width for the passed in region. The region is defined by the path closest to `(bounds.x, bounds.y)` and ends at `bounds.height + bounds.y`. If `bounds` is `null`, the preferred width for all the nodes will be returned (and this may be a VERY expensive computation).
      Parameters:
        `bounds` - the region being queried
      Returns:
        the preferred width for the passed in region

    - #### isExpanded

          public abstract boolean isExpanded(TreePath path)

      Returns true if the value identified by row is currently expanded.

    - #### getBounds

          public abstract Rectangle getBounds(TreePath path,
                                              Rectangle placeIn)

      Returns a rectangle giving the bounds needed to draw path.
      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 abstract TreePath getPathForRow(int row)

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

    - #### getRowForPath

          public abstract 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.
      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 abstract 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.
      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

    - #### getVisiblePathsFrom

          public abstract 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. The first element of the returned enumeration will be path, unless it isn't visible, in which case `null` will be returned.
      Parameters:
        `path` - the starting location for the enumeration
      Returns:
        the `Enumerator` starting at the desired location

    - #### getVisibleChildCount

          public abstract int getVisibleChildCount(TreePath path)

      Returns the number of visible children for row.
      Parameters:
        `path` - the path being queried
      Returns:
        the number of visible children for the specified path

    - #### setExpandedState

          public abstract void setExpandedState(TreePath path,
                                                boolean isExpanded)

      Marks the path `path` expanded state to `isExpanded`.
      Parameters:
        `path` - the path being expanded or collapsed
        `isExpanded` - true if the path should be expanded, false otherwise

    - #### getExpandedState

          public abstract boolean getExpandedState(TreePath path)

      Returns true if the path is expanded, and visible.
      Parameters:
        `path` - the path being queried
      Returns:
        true if the path is expanded and visible, false otherwise

    - #### getRowCount

          public abstract int getRowCount()

      Number of rows being displayed.
      Returns:
        the number of rows being displayed

    - #### invalidateSizes

          public abstract void invalidateSizes()

      Informs the `TreeState` that it needs to recalculate all the sizes it is referencing.

    - #### invalidatePathBounds

          public abstract void invalidatePathBounds(TreePath path)

      Instructs the `LayoutCache` that the bounds for `path` are invalid, and need to be updated.
      Parameters:
        `path` - the path being updated

    - #### treeNodesChanged

          public abstract 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).

      Parameters:
        `e` - the `TreeModelEvent`

    - #### treeNodesInserted

          public abstract 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.

      Parameters:
        `e` - the `TreeModelEvent`

    - #### treeNodesRemoved

          public abstract 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.

      Parameters:
        `e` - the `TreeModelEvent`

    - #### treeStructureChanged

          public abstract 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.

      Parameters:
        `e` - the `TreeModelEvent`

    - #### getRowsForPaths

          public int[] getRowsForPaths(TreePath[] paths)

      Returns the rows that the `TreePath` instances in `path` are being displayed at. This method should return an array of the same length as that passed in, and if one of the `TreePaths` in `path` is not valid its entry in the array should be set to -1.
      Specified by:
        `getRowsForPaths` in interface `RowMapper`
      Parameters:
        `paths` - the array of `TreePath`s being queried
      Returns:
        an array of the same length that is passed in containing the rows that each corresponding where each `TreePath` is displayed; if `paths` is `null`, `null` is returned

    - #### getNodeDimensions

          protected Rectangle getNodeDimensions(Object value,
                                                int row,
                                                int depth,
                                                boolean expanded,
                                                Rectangle placeIn)

      Returns, by reference in `placeIn`, the size needed to represent `value`. If `inPlace` is `null`, a newly created `Rectangle` should be returned, otherwise the value should be placed in `inPlace` and returned. This will return `null` if there is no renderer.
      Parameters:
        `value` - the `value` to be represented
        `row` - row being queried
        `depth` - the depth of the row
        `expanded` - true if row is expanded, false otherwise
        `placeIn` - a `Rectangle` containing the size needed to represent `value`
      Returns:
        a `Rectangle` containing the node dimensions, or `null` if node has no dimension

    - #### isFixedRowHeight

          protected boolean isFixedRowHeight()

      Returns true if the height of each row is a fixed size.

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