/*
* @(#)TreePath.java 1.29 03/12/19
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.swing.tree;
import java.io.*;
import java.util.Vector;
/**
* Represents a path to a node. A TreePath is an array of Objects that are
* vended from a TreeModel. The elements of the array are ordered such
* that the root is always the first element (index 0) of the array.
* TreePath is Serializable, but if any
* components of the path are not serializable, it will not be written
* out.
* <p>
* For further information and examples of using tree paths,
* see <a
href="http://java.sun.com/docs/books/tutorial/uiswing/components/tree.html">How to Use Trees</a>
* in <em>The Java Tutorial.</em>
* <p>
* <strong>Warning:</strong>
* 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<sup><font size="-2">TM</font></sup>
* has been added to the <code>java.beans</code> package.
* Please see {@link java.beans.XMLEncoder}.
*
* @version 1.29 12/19/03
* @author Scott Violet
* @author Philip Milne
*/
public class TreePath extends Object implements Serializable {
/** Path representing the parent, null if lastPathComponent represents
* the root. */
private TreePath parentPath;
/** Last path component. */
transient private Object lastPathComponent;
/**
* Constructs a path from an array of Objects, uniquely identifying
* the path from the root of the tree to a specific node, as returned
* by the tree's data model.
* <p>
* The model is free to return an array of any Objects it needs to
* represent the path. The DefaultTreeModel returns an array of
* TreeNode objects. The first TreeNode in the path is the root of the
* tree, the last TreeNode is the node identified by the path.
*
* @param path an array of Objects representing the path to a node
*/
public TreePath(Object[] path) {
if(path == null || path.length == 0)
throw new IllegalArgumentException("path in TreePath must be non null and not empty.");
lastPathComponent = path[path.length - 1];
if(path.length > 1)
parentPath = new TreePath(path, path.length - 1);
}
/**
* Constructs a TreePath containing only a single element. This is
* usually used to construct a TreePath for the the root of the TreeModel.
* <p>
* @param singlePath an Object representing the path to a node
* @see #TreePath(Object[])
*/
public TreePath(Object singlePath) {
if(singlePath == null)
throw new IllegalArgumentException("path in TreePath must be non null.");
lastPathComponent = singlePath;
parentPath = null;
}
/**
* Constructs a new TreePath, which is the path identified by
* <code>parent</code> ending in <code>lastElement</code>.
*/
protected TreePath(TreePath parent, Object lastElement) {
if(lastElement == null)
throw new IllegalArgumentException("path in TreePath must be non null.");
parentPath = parent;
lastPathComponent = lastElement;
}
/**
* Constructs a new TreePath with the identified path components of
* length <code>length</code>.
*/
protected TreePath(Object[] path, int length) {
lastPathComponent = path[length - 1];
if(length > 1)
parentPath = new TreePath(path, length - 1);
}
/**
* Primarily provided for subclasses
* that represent paths in a different manner.
* If a subclass uses this constructor, it should also override
* the <code>getPath</code>,
* <code>getPathCount</code>, and
* <code>getPathComponent</code> methods,
* and possibly the <code>equals</code> method.
*/
protected TreePath() {
}
/**
* Returns an ordered array of Objects containing the components of this
* TreePath. The first element (index 0) is the root.
*
* @return an array of Objects representing the TreePath
* @see #TreePath(Object[])
*/
public Object[] getPath() {
int i = getPathCount();
Object[] result = new Object[i--];
for(TreePath path = this; path != null; path = path.parentPath) {
result[i--] = path.lastPathComponent;
}
return result;
}
/**
* Returns the last component of this path. For a path returned by
* DefaultTreeModel this will return an instance of TreeNode.
*
* @return the Object at the end of the path
* @see #TreePath(Object[])
*/
public Object getLastPathComponent() {
return lastPathComponent;
}
/**
* Returns the number of elements in the path.
*
* @return an int giving a count of items the path
*/
public int getPathCount() {
int result = 0;
for(TreePath path = this; path != null; path = path.parentPath) {
result++;
}
return result;
}
/**
* Returns the path component at the specified index.
*
* @param element an int specifying an element in the path, where
* 0 is the first element in the path
* @return the Object at that index location
* @throws IllegalArgumentException if the index is beyond the length
* of the path
* @see #TreePath(Object[])
*/
public Object getPathComponent(int element) {
int pathLength = getPathCount();
if(element < 0 || element >= pathLength)
throw new IllegalArgumentException("Index " + element + " is out of the specified range");
TreePath path = this;
for(int i = pathLength-1; i != element; i--) {
path = path.parentPath;
}
return path.lastPathComponent;
}
/**
* Tests two TreePaths for equality by checking each element of the
* paths for equality. Two paths are considered equal if they are of
* the same length, and contain
* the same elements (<code>.equals</code>).
*
* @param o the Object to compare
*/
public boolean equals(Object o) {
if(o == this)
return true;
if(o instanceof TreePath) {
TreePath oTreePath = (TreePath)o;
if(getPathCount() != oTreePath.getPathCount())
return false;
for(TreePath path = this; path != null; path = path.parentPath) {
if (!(path.lastPathComponent.equals
(oTreePath.lastPathComponent))) {
return false;
}
oTreePath = oTreePath.parentPath;
}
return true;
}
return false;
}
/**
* Returns the hashCode for the object. The hash code of a TreePath
* is defined to be the hash code of the last component in the path.
*
* @return the hashCode for the object
*/
public int hashCode() {
return lastPathComponent.hashCode();
}
/**
* Returns true if <code>aTreePath</code> is a
* descendant of this
* TreePath. A TreePath P1 is a descendent of a TreePath P2
* if P1 contains all of the components that make up
* P2's path.
* For example, if this object has the path [a, b],
* and <code>aTreePath</code> has the path [a, b, c],
* then <code>aTreePath</code> is a descendant of this object.
* However, if <code>aTreePath</code> has the path [a],
* then it is not a descendant of this object.
*
* @return true if <code>aTreePath</code> is a descendant of this path
*/
public boolean isDescendant(TreePath aTreePath) {
if(aTreePath == this)
return true;
if(aTreePath != null) {
int pathLength = getPathCount();
int oPathLength = aTreePath.getPathCount();
if(oPathLength < pathLength)
// Can't be a descendant, has fewer components in the path.
return false;
while(oPathLength-- > pathLength)
aTreePath = aTreePath.getParentPath();
return equals(aTreePath);
}
return false;
}
/**
* Returns a new path containing all the elements of this object
* plus <code>child</code>. <code>child</code> will be the last element
* of the newly created TreePath.
* This will throw a NullPointerException
* if child is null.
*/
public TreePath pathByAddingChild(Object child) {
if(child == null)
throw new NullPointerException("Null child not allowed");
return new TreePath(this, child);
}
/**
* Returns a path containing all the elements of this object, except
* the last path component.
*/
public TreePath getParentPath() {
return parentPath;
}
/**
* Returns a string that displays and identifies this
* object's properties.
*
* @return a String representation of this object
*/
public String toString() {
StringBuffer tempSpot = new StringBuffer("[");
for(int counter = 0, maxCounter = getPathCount();counter < maxCounter;
counter++) {
if(counter > 0)
tempSpot.append(", ");
tempSpot.append(getPathComponent(counter));
}
tempSpot.append("]");
return tempSpot.toString();
}
// Serialization support.
private void writeObject(ObjectOutputStream s) throws IOException {
s.defaultWriteObject();
Vector values = new Vector();
boolean writePath = true;
if(lastPathComponent != null &&
(lastPathComponent instanceof Serializable)) {
values.addElement("lastPathComponent");
values.addElement(lastPathComponent);
}
s.writeObject(values);
}
private void readObject(ObjectInputStream s)
throws IOException, ClassNotFoundException {
s.defaultReadObject();
Vector values = (Vector)s.readObject();
int indexCounter = 0;
int maxCounter = values.size();
if(indexCounter < maxCounter && values.elementAt(indexCounter).
equals("lastPathComponent")) {
lastPathComponent = values.elementAt(++indexCounter);
indexCounter++;
}
}
}
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