* {@code TreePath} is used extensively by {@code JTree} and related classes. * For example, {@code JTree} represents the selection as an array of * {@code TreePath}s. When used with {@code JTree}, the elements of the * path are the objects returned from the {@code TreeModel}. When {@code JTree} * is paired with {@code DefaultTreeModel}, the elements of the * path are {@code TreeNode}s. The following example illustrates extracting * the user object from the selection of a {@code JTree}: *
* DefaultMutableTreeNode root = ...; * DefaultTreeModel model = new DefaultTreeModel(root); * JTree tree = new JTree(model); * ... * TreePath selectedPath = tree.getSelectionPath(); * DefaultMutableTreeNode selectedNode = * ((DefaultMutableTreeNode)selectedPath.getLastPathComponent()). * getUserObject(); ** Subclasses typically need override only {@code * getLastPathComponent}, and {@code getParentPath}. As {@code JTree} * internally creates {@code TreePath}s at various points, it's * generally not useful to subclass {@code TreePath} and use with * {@code JTree}. *
* While {@code TreePath} is serializable, a {@code * NotSerializableException} is thrown if any elements of the path are * not serializable. *
* For further information and examples of using tree paths, * see How to Use Trees * in The Java Tutorial. *
* 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 {@link java.beans.XMLEncoder}.
*
* @author Scott Violet
* @author Philip Milne
*/
@SuppressWarnings("serial") // Same-version serialization only
public class TreePath extends Object implements Serializable {
/** Path representing the parent, null if lastPathComponent represents
* the root. */
private TreePath parentPath;
/** Last path component. */
private Object lastPathComponent;
/**
* Creates a {@code TreePath} from an array. The array uniquely
* identifies the path to a node.
*
* @param path an array of objects representing the path to a node
* @throws IllegalArgumentException if {@code path} is {@code null},
* empty, or contains a {@code null} value
*/
@ConstructorProperties({"path"})
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 (lastPathComponent == null) {
throw new IllegalArgumentException(
"Last path component must be non-null");
}
if(path.length > 1)
parentPath = new TreePath(path, path.length - 1);
}
/**
* Creates a {@code TreePath} containing a single element. This is
* used to construct a {@code TreePath} identifying the root.
*
* @param lastPathComponent the root
* @see #TreePath(Object[])
* @throws IllegalArgumentException if {@code lastPathComponent} is
* {@code null}
*/
public TreePath(Object lastPathComponent) {
if(lastPathComponent == null)
throw new IllegalArgumentException("path in TreePath must be non null.");
this.lastPathComponent = lastPathComponent;
parentPath = null;
}
/**
* Creates a {@code TreePath} with the specified parent and element.
*
* @param parent the path to the parent, or {@code null} to indicate
* the root
* @param lastPathComponent the last path element
* @throws IllegalArgumentException if {@code lastPathComponent} is
* {@code null}
*/
protected TreePath(TreePath parent, Object lastPathComponent) {
if(lastPathComponent == null)
throw new IllegalArgumentException("path in TreePath must be non null.");
parentPath = parent;
this.lastPathComponent = lastPathComponent;
}
/**
* Creates a {@code TreePath} from an array. The returned
* {@code TreePath} represents the elements of the array from
* {@code 0} to {@code length - 1}.
*
* This constructor is used internally, and generally not useful outside
* of subclasses.
*
* @param path the array to create the {@code TreePath} from
* @param length identifies the number of elements in {@code path} to
* create the {@code TreePath} from
* @throws NullPointerException if {@code path} is {@code null}
* @throws ArrayIndexOutOfBoundsException if {@code length - 1} is
* outside the range of the array
* @throws IllegalArgumentException if any of the elements from
* {@code 0} to {@code length - 1} are {@code null}
*/
protected TreePath(Object[] path, int length) {
lastPathComponent = path[length - 1];
if (lastPathComponent == null) {
throw new IllegalArgumentException(
"Path elements must be non-null");
}
if(length > 1)
parentPath = new TreePath(path, length - 1);
}
/**
* Creates an empty {@code TreePath}. This is provided for
* subclasses that represent paths in a different
* manner. Subclasses that use this constructor must override
* {@code getLastPathComponent}, and {@code getParentPath}.
*/
protected TreePath() {
}
/**
* Returns an ordered array of the elements of this {@code TreePath}.
* The first element is the root.
*
* @return an array of the elements in this {@code TreePath}
*/
public Object[] getPath() {
int i = getPathCount();
Object[] result = new Object[i--];
for(TreePath path = this; path != null; path = path.getParentPath()) {
result[i--] = path.getLastPathComponent();
}
return result;
}
/**
* Returns the last element of this path.
*
* @return the last element in the path
*/
public Object getLastPathComponent() {
return lastPathComponent;
}
/**
* Returns the number of elements in the path.
*
* @return the number of elements in the path
*/
public int getPathCount() {
int result = 0;
for(TreePath path = this; path != null; path = path.getParentPath()) {
result++;
}
return result;
}
/**
* Returns the path element at the specified index.
*
* @param index the index of the element requested
* @return the element at the specified index
* @throws IllegalArgumentException if the index is outside the
* range of this path
*/
public Object getPathComponent(int index) {
int pathLength = getPathCount();
if(index < 0 || index >= pathLength)
throw new IllegalArgumentException("Index " + index +
" is out of the specified range");
TreePath path = this;
for(int i = pathLength-1; i != index; i--) {
path = path.getParentPath();
}
return path.getLastPathComponent();
}
/**
* Compares this {@code TreePath} to the specified object. This returns
* {@code true} if {@code o} is a {@code TreePath} with the exact
* same elements (as determined by using {@code equals} on each
* element of the path).
*
* @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.getParentPath()) {
if (!(path.getLastPathComponent().equals
(oTreePath.getLastPathComponent()))) {
return false;
}
oTreePath = oTreePath.getParentPath();
}
return true;
}
return false;
}
/**
* Returns the hash code of this {@code TreePath}. The hash code of a
* {@code TreePath} is the hash code of the last element in the path.
*
* @return the hashCode for the object
*/
public int hashCode() {
return getLastPathComponent().hashCode();
}
/**
* Returns true if aTreePath is a
* descendant of this
* {@code TreePath}. A {@code TreePath} {@code P1} is a descendant of a
* {@code TreePath} {@code P2}
* if {@code P1} contains all of the elements that make up
* {@code P2's} path.
* For example, if this object has the path {@code [a, b]},
* and aTreePath has the path {@code [a, b, c]},
* then aTreePath is a descendant of this object.
* However, if aTreePath has the path {@code [a]},
* then it is not a descendant of this object. By this definition
* a {@code TreePath} is always considered a descendant of itself.
* That is, aTreePath.isDescendant(aTreePath) returns
* {@code true}.
*
* @param aTreePath the {@code TreePath} to check
* @return true if aTreePath 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 path
* plus child. child is the last element
* of the newly created {@code TreePath}.
*
* @param child the path element to add
* @throws NullPointerException if {@code child} is {@code null}
*/
public TreePath pathByAddingChild(Object child) {
if(child == null)
throw new NullPointerException("Null child not allowed");
return new TreePath(this, child);
}
/**
* Returns the {@code TreePath} of the parent. A return value of
* {@code null} indicates this is the root node.
*
* @return the parent path
*/
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();
}
}