OptionsTreeModel.java

package com.limegroup.gnutella.gui.options;

import java.io.IOException;

import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.MutableTreeNode;

/**
 * This class creates the <tt>TreeModel</tt> used in the <tt>JTree</tt> of 
 * the options pane.
 */
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final class OptionsTreeModel extends DefaultTreeModel {

	/**
	 * Constant handle to the root node of the tree.
	 */
	private OptionsTreeNode ROOT = null;		

	/**
	 * The constructor constructs the <tt>MutableTreeNode</tt> instances
	 * as well as the <tt>TreeModel</tt>.
	 */
	OptionsTreeModel() {
		super(null);
		ROOT = new OptionsTreeNode(OptionsMediator.ROOT_NODE_KEY, "");
		setRoot(ROOT);
	}

	/**
	 * Adds a new <tt>OptionsTreeNode</tt> to one of the root node's
	 * children.  This should only be called during tree construction.
	 * The first key cannot denote the root.
	 *
	 * @param parentKey the unique identifying key of the node to add as
	 *                  well as the key for the locale-specific name for
	 *                  the node as it appears to the user
	 *
	 * @param key the unique identifying key of the node to add as well as
	 *            the key for the locale-specific name for the node as it
	 *            appears to the user
	 *
	 * @param displayName the name of the node as it is displayed to the
	 *                    user
	 * @throws IllegalArgumentException if the parentKey does not
	 *                                  correspond to any top-level node
	 *                                  in the tree
	 */
	final void addNode(
			final String parentKey,
			final String key,
			final String displayName) {
		MutableTreeNode newNode = new OptionsTreeNode(key, displayName);
		MutableTreeNode parentNode;

		if (parentKey == OptionsMediator.ROOT_NODE_KEY) {
			parentNode = ROOT;
		} else {
			try {
				parentNode = getParentNode(ROOT, parentKey);
			} catch (IOException ioe) {
				//the parent node could not be found, so return
				return;
			}
			if (parentNode == null)
				return;
		}
		
		// insert the new node
		insertNodeInto(newNode, parentNode, parentNode.getChildCount());
		reload(parentNode);
	}

	/**
	 * This method performs a recursive depth-first search for the
	 * parent node with the specified key.
	 *
	 * @param node the current node to search through
	 * @param parentKey the key that will match the key of the parent node
	 *                  we are searching for
	 * @return the <tt>MutableTreeNode</tt> instance corresponding to
	 *         the specified key, or <tt>null</tt> if it could not be found
	 * @throws IOException if a corresponding key does not exist
	 */
	private final MutableTreeNode getParentNode(
			MutableTreeNode node,
			final String parentKey) 
			throws IOException {
		// note that we use the key to denote equality, as each node may
		// have the same visual name, but it will not have the same key
		for (int i = 0, length = node.getChildCount(); i < length; i++) {
			OptionsTreeNode curNode =
				(OptionsTreeNode)node.getChildAt(i);

			if (curNode.getTitleKey().equals((parentKey)))
				return curNode;
			getParentNode(curNode, parentKey);
			
			if (curNode.isRoot() && i == (length - 1)) {
				// this means we have looped through all of the nodes
				// without finding the parent key, so throw an exception
				String msg = "Parent node not in options tree.";
				throw new IOException(msg);
			}
		}
		
		// this will never happen -- the exception should always be thrown
		return null;
	}

}