public class DefaultMutableTreeNode extends Object implements Cloneable, MutableTreeNode, Serializable
DefaultMutableTreeNode
is a general-purpose node in a tree data
structure.
For examples of using default mutable tree nodes, see
How to Use Trees
in The Java Tutorial.
A tree node may have at most one parent and 0 or more children.
DefaultMutableTreeNode
provides operations for examining and modifying a
node's parent and children and also operations for examining the tree that
the node is a part of. A node's tree is the set of all nodes that can be
reached by starting at the node and following all the possible links to
parents and children. A node with no parent is the root of its tree; a
node with no children is a leaf. A tree may consist of many subtrees,
each node acting as the root for its own subtree.
This class provides enumerations for efficiently traversing a tree or
subtree in various orders or for following the path between two nodes.
A DefaultMutableTreeNode
may also hold a reference to a user object, the
use of which is left to the user. Asking a DefaultMutableTreeNode
for its
string representation with toString()
returns the string
representation of its user object.
This is not a thread safe class.If you intend to use a DefaultMutableTreeNode (or a tree of TreeNodes) in more than one thread, you need to do your own synchronizing. A good convention to adopt is synchronizing on the root node of a tree.
While DefaultMutableTreeNode implements the MutableTreeNode interface and will allow you to add in any implementation of MutableTreeNode not all of the methods in DefaultMutableTreeNode will be applicable to all MutableTreeNodes implementations. Especially with some of the enumerations that are provided, using some of these methods assumes the DefaultMutableTreeNode contains only DefaultMutableNode instances. All of the TreeNode/MutableTreeNode methods will behave as defined no matter what implementations are added.
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 JavaBeansTM
has been added to the java.beans
package.
Please see XMLEncoder
.
MutableTreeNode
Modifier and Type | Field and Description |
---|---|
protected boolean |
allowsChildren
true if the node is able to have children
|
protected Vector |
children
array of children, may be null if this node has no children
|
static Enumeration<TreeNode> |
EMPTY_ENUMERATION
An enumeration that is always empty.
|
protected MutableTreeNode |
parent
this node's parent, or null if this node has no parent
|
protected Object |
userObject
optional user object
|
Constructor and Description |
---|
DefaultMutableTreeNode()
Creates a tree node that has no parent and no children, but which
allows children.
|
DefaultMutableTreeNode(Object userObject)
Creates a tree node with no parent, no children, but which allows
children, and initializes it with the specified user object.
|
DefaultMutableTreeNode(Object userObject,
boolean allowsChildren)
Creates a tree node with no parent, no children, initialized with
the specified user object, and that allows children only if
specified.
|
Modifier and Type | Method and Description |
---|---|
void |
add(MutableTreeNode newChild)
Removes
newChild from its parent and makes it a child of
this node by adding it to the end of this node's child array. |
Enumeration |
breadthFirstEnumeration()
Creates and returns an enumeration that traverses the subtree rooted at
this node in breadth-first order.
|
Enumeration |
children()
Creates and returns a forward-order enumeration of this node's
children.
|
Object |
clone()
Overridden to make clone public.
|
Enumeration |
depthFirstEnumeration()
Creates and returns an enumeration that traverses the subtree rooted at
this node in depth-first order.
|
boolean |
getAllowsChildren()
Returns true if this node is allowed to have children.
|
TreeNode |
getChildAfter(TreeNode aChild)
Returns the child in this node's child array that immediately
follows
aChild , which must be a child of this node. |
TreeNode |
getChildAt(int index)
Returns the child at the specified index in this node's child array.
|
TreeNode |
getChildBefore(TreeNode aChild)
Returns the child in this node's child array that immediately
precedes
aChild , which must be a child of this node. |
int |
getChildCount()
Returns the number of children of this node.
|
int |
getDepth()
Returns the depth of the tree rooted at this node -- the longest
distance from this node to a leaf.
|
TreeNode |
getFirstChild()
Returns this node's first child.
|
DefaultMutableTreeNode |
getFirstLeaf()
Finds and returns the first leaf that is a descendant of this node --
either this node or its first child's first leaf.
|
int |
getIndex(TreeNode aChild)
Returns the index of the specified child in this node's child array.
|
TreeNode |
getLastChild()
Returns this node's last child.
|
DefaultMutableTreeNode |
getLastLeaf()
Finds and returns the last leaf that is a descendant of this node --
either this node or its last child's last leaf.
|
int |
getLeafCount()
Returns the total number of leaves that are descendants of this node.
|
int |
getLevel()
Returns the number of levels above this node -- the distance from
the root to this node.
|
DefaultMutableTreeNode |
getNextLeaf()
Returns the leaf after this node or null if this node is the
last leaf in the tree.
|
DefaultMutableTreeNode |
getNextNode()
Returns the node that follows this node in a preorder traversal of this
node's tree.
|
DefaultMutableTreeNode |
getNextSibling()
Returns the next sibling of this node in the parent's children array.
|
TreeNode |
getParent()
Returns this node's parent or null if this node has no parent.
|
TreeNode[] |
getPath()
Returns the path from the root, to get to this node.
|
protected TreeNode[] |
getPathToRoot(TreeNode aNode,
int depth)
Builds the parents of node up to and including the root node,
where the original node is the last element in the returned array.
|
DefaultMutableTreeNode |
getPreviousLeaf()
Returns the leaf before this node or null if this node is the
first leaf in the tree.
|
DefaultMutableTreeNode |
getPreviousNode()
Returns the node that precedes this node in a preorder traversal of
this node's tree.
|
DefaultMutableTreeNode |
getPreviousSibling()
Returns the previous sibling of this node in the parent's children
array.
|
TreeNode |
getRoot()
Returns the root of the tree that contains this node.
|
TreeNode |
getSharedAncestor(DefaultMutableTreeNode aNode)
Returns the nearest common ancestor to this node and
aNode . |
int |
getSiblingCount()
Returns the number of siblings of this node.
|
Object |
getUserObject()
Returns this node's user object.
|
Object[] |
getUserObjectPath()
Returns the user object path, from the root, to get to this node.
|
void |
insert(MutableTreeNode newChild,
int childIndex)
Removes
newChild from its present parent (if it has a
parent), sets the child's parent to this node, and then adds the child
to this node's child array at index childIndex . |
boolean |
isLeaf()
Returns true if this node has no children.
|
boolean |
isNodeAncestor(TreeNode anotherNode)
Returns true if
anotherNode is an ancestor of this node
-- if it is this node, this node's parent, or an ancestor of this
node's parent. |
boolean |
isNodeChild(TreeNode aNode)
Returns true if
aNode is a child of this node. |
boolean |
isNodeDescendant(DefaultMutableTreeNode anotherNode)
Returns true if
anotherNode is a descendant of this node
-- if it is this node, one of this node's children, or a descendant of
one of this node's children. |
boolean |
isNodeRelated(DefaultMutableTreeNode aNode)
Returns true if and only if
aNode is in the same tree
as this node. |
boolean |
isNodeSibling(TreeNode anotherNode)
Returns true if
anotherNode is a sibling of (has the
same parent as) this node. |
boolean |
isRoot()
Returns true if this node is the root of the tree.
|
Enumeration |
pathFromAncestorEnumeration(TreeNode ancestor)
Creates and returns an enumeration that follows the path from
ancestor to this node. |
Enumeration |
postorderEnumeration()
Creates and returns an enumeration that traverses the subtree rooted at
this node in postorder.
|
Enumeration |
preorderEnumeration()
Creates and returns an enumeration that traverses the subtree rooted at
this node in preorder.
|
void |
remove(int childIndex)
Removes the child at the specified index from this node's children
and sets that node's parent to null.
|
void |
remove(MutableTreeNode aChild)
Removes
aChild from this node's child array, giving it a
null parent. |
void |
removeAllChildren()
Removes all of this node's children, setting their parents to null.
|
void |
removeFromParent()
Removes the subtree rooted at this node from the tree, giving this
node a null parent.
|
void |
setAllowsChildren(boolean allows)
Determines whether or not this node is allowed to have children.
|
void |
setParent(MutableTreeNode newParent)
Sets this node's parent to
newParent but does not
change the parent's child array. |
void |
setUserObject(Object userObject)
Sets the user object for this node to
userObject . |
String |
toString()
Returns the result of sending
toString() to this node's
user object, or the empty string if the node has no user object. |
public static final Enumeration<TreeNode> EMPTY_ENUMERATION
protected MutableTreeNode parent
protected Vector children
protected transient Object userObject
protected boolean allowsChildren
public DefaultMutableTreeNode()
public DefaultMutableTreeNode(Object userObject)
userObject
- an Object provided by the user that constitutes
the node's datapublic DefaultMutableTreeNode(Object userObject, boolean allowsChildren)
userObject
- an Object provided by the user that constitutes
the node's dataallowsChildren
- if true, the node is allowed to have child
nodes -- otherwise, it is always a leaf nodepublic void insert(MutableTreeNode newChild, int childIndex)
newChild
from its present parent (if it has a
parent), sets the child's parent to this node, and then adds the child
to this node's child array at index childIndex
.
newChild
must not be null and must not be an ancestor of
this node.insert
in interface MutableTreeNode
newChild
- the MutableTreeNode to insert under this nodechildIndex
- the index in this node's child array
where this node is to be insertedArrayIndexOutOfBoundsException
- if
childIndex
is out of boundsIllegalArgumentException
- if
newChild
is null or is an
ancestor of this nodeIllegalStateException
- if this node does not allow
childrenisNodeDescendant(javax.swing.tree.DefaultMutableTreeNode)
public void remove(int childIndex)
MutableTreeNode
.remove
in interface MutableTreeNode
childIndex
- the index in this node's child array
of the child to removeArrayIndexOutOfBoundsException
- if
childIndex
is out of boundspublic void setParent(MutableTreeNode newParent)
newParent
but does not
change the parent's child array. This method is called from
insert()
and remove()
to
reassign a child's parent, it should not be messaged from anywhere
else.setParent
in interface MutableTreeNode
newParent
- this node's new parentpublic TreeNode getParent()
public TreeNode getChildAt(int index)
getChildAt
in interface TreeNode
index
- an index into this node's child arrayArrayIndexOutOfBoundsException
- if index
is out of boundspublic int getChildCount()
getChildCount
in interface TreeNode
public int getIndex(TreeNode aChild)
-1
. This method performs a linear search and is O(n)
where n is the number of children.getIndex
in interface TreeNode
aChild
- the TreeNode to search for among this node's children-1
if the specified node is a not
a child of this nodeIllegalArgumentException
- if aChild
is nullpublic Enumeration children()
public void setAllowsChildren(boolean allows)
allows
is false, all of this node's children are
removed.
Note: By default, a node allows children.
allows
- true if this node is allowed to have childrenpublic boolean getAllowsChildren()
getAllowsChildren
in interface TreeNode
public void setUserObject(Object userObject)
userObject
.setUserObject
in interface MutableTreeNode
userObject
- the Object that constitutes this node's
user-specified datagetUserObject()
,
toString()
public Object getUserObject()
setUserObject(java.lang.Object)
,
toString()
public void removeFromParent()
removeFromParent
in interface MutableTreeNode
public void remove(MutableTreeNode aChild)
aChild
from this node's child array, giving it a
null parent.remove
in interface MutableTreeNode
aChild
- a child of this node to removeIllegalArgumentException
- if aChild
is null or is not a child of this nodepublic void removeAllChildren()
public void add(MutableTreeNode newChild)
newChild
from its parent and makes it a child of
this node by adding it to the end of this node's child array.newChild
- node to add as a child of this nodeIllegalArgumentException
- if newChild
is nullIllegalStateException
- if this node does not allow
childreninsert(javax.swing.tree.MutableTreeNode, int)
public boolean isNodeAncestor(TreeNode anotherNode)
anotherNode
is an ancestor of this node
-- if it is this node, this node's parent, or an ancestor of this
node's parent. (Note that a node is considered an ancestor of itself.)
If anotherNode
is null, this method returns false. This
operation is at worst O(h) where h is the distance from the root to
this node.anotherNode
- node to test as an ancestor of this nodeanotherNode
isNodeDescendant(javax.swing.tree.DefaultMutableTreeNode)
,
getSharedAncestor(javax.swing.tree.DefaultMutableTreeNode)
public boolean isNodeDescendant(DefaultMutableTreeNode anotherNode)
anotherNode
is a descendant of this node
-- if it is this node, one of this node's children, or a descendant of
one of this node's children. Note that a node is considered a
descendant of itself. If anotherNode
is null, returns
false. This operation is at worst O(h) where h is the distance from the
root to anotherNode
.anotherNode
- node to test as descendant of this nodeanotherNode
isNodeAncestor(javax.swing.tree.TreeNode)
,
getSharedAncestor(javax.swing.tree.DefaultMutableTreeNode)
public TreeNode getSharedAncestor(DefaultMutableTreeNode aNode)
aNode
.
Returns null, if no such ancestor exists -- if this node and
aNode
are in different trees or if aNode
is
null. A node is considered an ancestor of itself.aNode
- node to find common ancestor withaNode
,
or null if noneisNodeAncestor(javax.swing.tree.TreeNode)
,
isNodeDescendant(javax.swing.tree.DefaultMutableTreeNode)
public boolean isNodeRelated(DefaultMutableTreeNode aNode)
aNode
is in the same tree
as this node. Returns false if aNode
is null.aNode
is in the same tree as this node;
false if aNode
is nullgetSharedAncestor(javax.swing.tree.DefaultMutableTreeNode)
,
getRoot()
public int getDepth()
getLevel()
because it must effectively traverse the entire
tree rooted at this node.getLevel()
public int getLevel()
getDepth()
public TreeNode[] getPath()
protected TreeNode[] getPathToRoot(TreeNode aNode, int depth)
aNode
- the TreeNode to get the path fordepth
- an int giving the number of steps already taken towards
the root (on recursive calls), used to size the returned arraypublic Object[] getUserObjectPath()
public TreeNode getRoot()
isNodeAncestor(javax.swing.tree.TreeNode)
public boolean isRoot()
public DefaultMutableTreeNode getNextNode()
preorderEnumeration()
public DefaultMutableTreeNode getPreviousNode()
null
if this node is the
first node of the traversal -- the root of the tree.
This is an inefficient way to
traverse the entire tree; use an enumeration, instead.preorderEnumeration()
public Enumeration preorderEnumeration()
nextElement()
method is this node.Modifying the tree by inserting, removing, or moving a node invalidates any enumerations created before the modification.
postorderEnumeration()
public Enumeration postorderEnumeration()
nextElement()
method is the leftmost leaf. This is the
same as a depth-first traversal.Modifying the tree by inserting, removing, or moving a node invalidates any enumerations created before the modification.
depthFirstEnumeration()
,
preorderEnumeration()
public Enumeration breadthFirstEnumeration()
nextElement()
method is this node.Modifying the tree by inserting, removing, or moving a node invalidates any enumerations created before the modification.
depthFirstEnumeration()
public Enumeration depthFirstEnumeration()
nextElement()
method is the leftmost leaf.
This is the same as a postorder traversal.Modifying the tree by inserting, removing, or moving a node invalidates any enumerations created before the modification.
breadthFirstEnumeration()
,
postorderEnumeration()
public Enumeration pathFromAncestorEnumeration(TreeNode ancestor)
ancestor
to this node. The enumeration's
nextElement()
method first returns ancestor
,
then the child of ancestor
that is an ancestor of this
node, and so on, and finally returns this node. Creation of the
enumeration is O(m) where m is the number of nodes between this node
and ancestor
, inclusive. Each nextElement()
message is O(1).Modifying the tree by inserting, removing, or moving a node invalidates any enumerations created before the modification.
IllegalArgumentException
- if ancestor
is
not an ancestor of this nodeisNodeAncestor(javax.swing.tree.TreeNode)
,
isNodeDescendant(javax.swing.tree.DefaultMutableTreeNode)
public boolean isNodeChild(TreeNode aNode)
aNode
is a child of this node. If
aNode
is null, this method returns false.aNode
is a child of this node; false if
aNode
is nullpublic TreeNode getFirstChild()
NoSuchElementException
- if this node has no childrenpublic TreeNode getLastChild()
NoSuchElementException
- if this node has no childrenpublic TreeNode getChildAfter(TreeNode aChild)
aChild
, which must be a child of this node. If
aChild
is the last child, returns null. This method
performs a linear search of this node's children for
aChild
and is O(n) where n is the number of children; to
traverse the entire array of children, use an enumeration instead.aChild
IllegalArgumentException
- if aChild
is
null or is not a child of this nodechildren
public TreeNode getChildBefore(TreeNode aChild)
aChild
, which must be a child of this node. If
aChild
is the first child, returns null. This method
performs a linear search of this node's children for aChild
and is O(n) where n is the number of children.aChild
IllegalArgumentException
- if aChild
is null
or is not a child of this nodepublic boolean isNodeSibling(TreeNode anotherNode)
anotherNode
is a sibling of (has the
same parent as) this node. A node is its own sibling. If
anotherNode
is null, returns false.anotherNode
- node to test as sibling of this nodeanotherNode
is a sibling of this nodepublic int getSiblingCount()
1
).public DefaultMutableTreeNode getNextSibling()
children
public DefaultMutableTreeNode getPreviousSibling()
public boolean isLeaf()
getAllowsChildren
isLeaf
in interface TreeNode
getAllowsChildren()
public DefaultMutableTreeNode getFirstLeaf()
isLeaf()
,
isNodeDescendant(javax.swing.tree.DefaultMutableTreeNode)
public DefaultMutableTreeNode getLastLeaf()
isLeaf()
,
isNodeDescendant(javax.swing.tree.DefaultMutableTreeNode)
public DefaultMutableTreeNode getNextLeaf()
In this implementation of the MutableNode
interface,
this operation is very inefficient. In order to determine the
next node, this method first performs a linear search in the
parent's child-list in order to find the current node.
That implementation makes the operation suitable for short
traversals from a known position. But to traverse all of the
leaves in the tree, you should use depthFirstEnumeration
to enumerate the nodes in the tree and use isLeaf
on each node to determine which are leaves.
depthFirstEnumeration()
,
isLeaf()
public DefaultMutableTreeNode getPreviousLeaf()
In this implementation of the MutableNode
interface,
this operation is very inefficient. In order to determine the
previous node, this method first performs a linear search in the
parent's child-list in order to find the current node.
That implementation makes the operation suitable for short
traversals from a known position. But to traverse all of the
leaves in the tree, you should use depthFirstEnumeration
to enumerate the nodes in the tree and use isLeaf
on each node to determine which are leaves.
depthFirstEnumeration()
,
isLeaf()
public int getLeafCount()
1
. This method is O(n)
where n is the number of descendants of this node.isNodeAncestor(javax.swing.tree.TreeNode)
public String toString()
toString()
to this node's
user object, or the empty string if the node has no user object.toString
in class Object
getUserObject()
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.
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