/**
* Returns the node that follows this node in a preorder traversal of this node's tree. Returns
* null if this node is the last node of the traversal. This is an inefficient way to traverse the
* entire tree; use an enumeration, instead.
*
* @see #preorderEnumeration
* @return the node that follows this node in a preorder traversal, or null if this node is last
*/
public DefaultMutableTreeNode getNextNode() {
if (getChildCount() == 0) {
// No children, so look for nextSibling
DefaultMutableTreeNode nextSibling = getNextSibling();
if (nextSibling == null) {
DefaultMutableTreeNode aNode = (DefaultMutableTreeNode) getParent();
do {
if (aNode == null) {
return null;
}
nextSibling = aNode.getNextSibling();
if (nextSibling != null) {
return nextSibling;
}
aNode = (DefaultMutableTreeNode) aNode.getParent();
} while (true);
} else {
return nextSibling;
}
} else {
return (DefaultMutableTreeNode) getChildAt(0);
}
}
/**
* Finds and returns the last leaf that is a descendant of this node -- either this node or its
* last child's last leaf. Returns this node if it is a leaf.
*
* @see #isLeaf
* @see #isNodeDescendant
* @return the last leaf in the subtree rooted at this node
*/
public DefaultMutableTreeNode getLastLeaf() {
DefaultMutableTreeNode node = this;
while (!node.isLeaf()) {
node = (DefaultMutableTreeNode) node.getLastChild();
}
return node;
}
/**
* Returns the leaf before this node or null if this node is the first leaf in the tree.
*
* <p>In this implementation of the <code>MutableNode</code> 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.
*
* <p>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 <code>depthFirstEnumeration
* </code> to enumerate the nodes in the tree and use <code>isLeaf</code> on each node to
* determine which are leaves.
*
* @see #depthFirstEnumeration
* @see #isLeaf
* @return returns the leaf before this node
*/
public DefaultMutableTreeNode getPreviousLeaf() {
DefaultMutableTreeNode previousSibling;
DefaultMutableTreeNode myParent = (DefaultMutableTreeNode) getParent();
if (myParent == null) return null;
previousSibling = getPreviousSibling(); // linear search
if (previousSibling != null) return previousSibling.getLastLeaf();
return myParent.getPreviousLeaf(); // tail recursion
}
/**
* Returns the leaf after this node or null if this node is the last leaf in the tree.
*
* <p>In this implementation of the <code>MutableNode</code> 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.
*
* <p>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 <code>depthFirstEnumeration
* </code> to enumerate the nodes in the tree and use <code>isLeaf</code> on each node to
* determine which are leaves.
*
* @see #depthFirstEnumeration
* @see #isLeaf
* @return returns the next leaf past this node
*/
public DefaultMutableTreeNode getNextLeaf() {
DefaultMutableTreeNode nextSibling;
DefaultMutableTreeNode myParent = (DefaultMutableTreeNode) getParent();
if (myParent == null) return null;
nextSibling = getNextSibling(); // linear search
if (nextSibling != null) return nextSibling.getFirstLeaf();
return myParent.getNextLeaf(); // tail recursion
}
/**
* Returns the previous sibling of this node in the parent's children array. Returns null if this
* node has no parent or is the parent's first child. This method performs a linear search that is
* O(n) where n is the number of children.
*
* @return the sibling of this node that immediately precedes this node
*/
public DefaultMutableTreeNode getPreviousSibling() {
DefaultMutableTreeNode retval;
DefaultMutableTreeNode myParent = (DefaultMutableTreeNode) getParent();
if (myParent == null) {
retval = null;
} else {
retval = (DefaultMutableTreeNode) myParent.getChildBefore(this); // linear search
}
if (retval != null && !isNodeSibling(retval)) {
throw new Error("child of parent is not a sibling");
}
return retval;
}
/**
* Returns the node that precedes this node in a preorder traversal of this node's tree. Returns
* <code>null</code> 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.
*
* @see #preorderEnumeration
* @return the node that precedes this node in a preorder traversal, or null if this node is the
* first
*/
public DefaultMutableTreeNode getPreviousNode() {
DefaultMutableTreeNode previousSibling;
DefaultMutableTreeNode myParent = (DefaultMutableTreeNode) getParent();
if (myParent == null) {
return null;
}
previousSibling = getPreviousSibling();
if (previousSibling != null) {
if (previousSibling.getChildCount() == 0) return previousSibling;
else return previousSibling.getLastLeaf();
} else {
return myParent;
}
}
/**
* Overridden to make clone public. Returns a shallow copy of this node; the new node has no
* parent or children and has a reference to the same user object, if any.
*
* @return a copy of this node
*/
public Object clone() {
DefaultMutableTreeNode newNode;
try {
newNode = (DefaultMutableTreeNode) super.clone();
// shallow copy -- the new node has no parent or children
newNode.children = null;
newNode.parent = null;
} catch (CloneNotSupportedException e) {
// Won't happen because we implement Cloneable
throw new Error(e.toString());
}
return newNode;
}
/**
* Returns the nearest common ancestor to this node and <code>aNode</code>. Returns null, if no
* such ancestor exists -- if this node and <code>aNode</code> are in different trees or if <code>
* aNode</code> is null. A node is considered an ancestor of itself.
*
* @see #isNodeAncestor
* @see #isNodeDescendant
* @param aNode node to find common ancestor with
* @return nearest ancestor common to this node and <code>aNode</code>, or null if none
*/
public TreeNode getSharedAncestor(DefaultMutableTreeNode aNode) {
if (aNode == this) {
return this;
} else if (aNode == null) {
return null;
}
int level1, level2, diff;
TreeNode node1, node2;
level1 = getLevel();
level2 = aNode.getLevel();
if (level2 > level1) {
diff = level2 - level1;
node1 = aNode;
node2 = this;
} else {
diff = level1 - level2;
node1 = this;
node2 = aNode;
}
// Go up the tree until the nodes are at the same level
while (diff > 0) {
node1 = node1.getParent();
diff--;
}
// Move up the tree until we find a common ancestor. Since we know
// that both nodes are at the same level, we won't cross paths
// unknowingly (if there is a common ancestor, both nodes hit it in
// the same iteration).
do {
if (node1 == node2) {
return node1;
}
node1 = node1.getParent();
node2 = node2.getParent();
} while (node1 != null); // only need to check one -- they're at the
// same level so if one is null, the other is
if (node1 != null || node2 != null) {
throw new Error("nodes should be null");
}
return null;
}
/**
* Returns true if and only if <code>aNode</code> is in the same tree as this node. Returns false
* if <code>aNode</code> is null.
*
* @see #getSharedAncestor
* @see #getRoot
* @return true if <code>aNode</code> is in the same tree as this node; false if <code>aNode
* </code> is null
*/
public boolean isNodeRelated(DefaultMutableTreeNode aNode) {
return (aNode != null) && (getRoot() == aNode.getRoot());
}
/**
* Returns true if <code>anotherNode</code> 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 <code>anotherNode</code> is null, returns false. This
* operation is at worst O(h) where h is the distance from the root to <code>anotherNode</code>.
*
* @see #isNodeAncestor
* @see #getSharedAncestor
* @param anotherNode node to test as descendant of this node
* @return true if this node is an ancestor of <code>anotherNode</code>
*/
public boolean isNodeDescendant(DefaultMutableTreeNode anotherNode) {
if (anotherNode == null) return false;
return anotherNode.isNodeAncestor(this);
}
