sampletree.java

java中關於tree的寫法,不同于往常

	  * Determines the selection from the Tree and adds an item
	  * after that.  If nothing is selected, an item is added to
	  * the root.
	  */
	public void actionPerformed(ActionEvent e) {
	    DefaultMutableTreeNode          lastItem = getSelectedNode();
	    DefaultMutableTreeNode          parent;

	    /* Determine where to create the new node. */
	    if(lastItem != null) {
		parent = (DefaultMutableTreeNode)lastItem.getParent();
		if(parent == null) {
		    parent = (DefaultMutableTreeNode)treeModel.getRoot();
		    lastItem = null;
		}
	    }
	    else
		parent = (DefaultMutableTreeNode)treeModel.getRoot();
            if (parent == null) {
                // new root
                treeModel.setRoot(createNewNode("Added " +
                                                Integer.toString(addCount++)));
            }
            else {
                int               newIndex;
                if(lastItem == null)
                    newIndex = treeModel.getChildCount(parent);
                else
                    newIndex = parent.getIndex(lastItem) + 1;

                /* Let the treemodel know. */
                treeModel.insertNodeInto(createNewNode("Added " +
                                    Integer.toString(addCount++)),
				    parent, newIndex);
            }
	}
    } // End of SampleTree.AddAction


    /**
      * InsertAction is used to insert a new item before the selected item.
      */
    class InsertAction extends Object implements ActionListener
    {
	/** Number of nodes that have been added. */
	public int               insertCount;

	/**
	  * Messaged when the user clicks on the Insert menu item.
	  * Determines the selection from the Tree and inserts an item
	  * after that.  If nothing is selected, an item is added to
	  * the root.
	  */
	public void actionPerformed(ActionEvent e) {
	    DefaultMutableTreeNode          lastItem = getSelectedNode();
	    DefaultMutableTreeNode          parent;

	    /* Determine where to create the new node. */
	    if(lastItem != null) {
		parent = (DefaultMutableTreeNode)lastItem.getParent();
		if(parent == null) {
		    parent = (DefaultMutableTreeNode)treeModel.getRoot();
		    lastItem = null;
		}
	    }
	    else
		parent = (DefaultMutableTreeNode)treeModel.getRoot();
            if (parent == null) {
                // new root
                treeModel.setRoot(createNewNode("Inserted " +
                                             Integer.toString(insertCount++)));
            }
            else {
                int               newIndex;

                if(lastItem == null)
                    newIndex = treeModel.getChildCount(parent);
                else
                    newIndex = parent.getIndex(lastItem);

                /* Let the treemodel know. */
                treeModel.insertNodeInto(createNewNode("Inserted " +
					 Integer.toString(insertCount++)),
                                         parent, newIndex);
            }
	}
    } // End of SampleTree.InsertAction


    /**
      * ReloadAction is used to reload from the selected node.  If nothing
      * is selected, reload is not issued.
      */
    class ReloadAction extends Object implements ActionListener
    {
	/**
	  * Messaged when the user clicks on the Reload menu item.
	  * Determines the selection from the Tree and asks the treemodel
	  * to reload from that node.
	  */
	public void actionPerformed(ActionEvent e) {
	    DefaultMutableTreeNode          lastItem = getSelectedNode();

	    if(lastItem != null)
		treeModel.reload(lastItem);
	}
    } // End of SampleTree.ReloadAction

    /**
      * RemoveAction removes the selected node from the tree.  If
      * The root or nothing is selected nothing is removed.
      */
    class RemoveAction extends Object implements ActionListener
    {
	/**
	  * Removes the selected item as long as it isn't root.
	  */
	public void actionPerformed(ActionEvent e) {
            TreePath[] selected = getSelectedPaths();

            if (selected != null && selected.length > 0) {
                TreePath shallowest;

                // The remove process consists of the following steps:
                // 1 - find the shallowest selected TreePath, the shallowest
                //     path is the path with the smallest number of path
                //     components.
                // 2 - Find the siblings of this TreePath
                // 3 - Remove from selected the TreePaths that are descendants
                //     of the paths that are going to be removed. They will
                //     be removed as a result of their ancestors being
                //     removed.
                // 4 - continue until selected contains only null paths.
                while ((shallowest = findShallowestPath(selected)) != null) {
                    removeSiblings(shallowest, selected);
                }
            }
	}

        /**
         * Removes the sibling TreePaths of <code>path</code>, that are
         * located in <code>paths</code>.
         */
        private void removeSiblings(TreePath path, TreePath[] paths) {
            // Find the siblings
            if (path.getPathCount() == 1) {
                // Special case, set the root to null
                for (int counter = paths.length - 1; counter >= 0; counter--) {
                    paths[counter] = null;
                }
                treeModel.setRoot(null);
            }
            else {
                // Find the siblings of path.
                TreePath parent = path.getParentPath();
                MutableTreeNode parentNode = (MutableTreeNode)parent.
                                getLastPathComponent();
                ArrayList toRemove = new ArrayList();
                int depth = parent.getPathCount();

                // First pass, find paths with a parent TreePath of parent
                for (int counter = paths.length - 1; counter >= 0; counter--) {
                    if (paths[counter] != null && paths[counter].
                              getParentPath().equals(parent)) {
                        toRemove.add(paths[counter]);
                        paths[counter] = null;
                    }
                }

                // Second pass, remove any paths that are descendants of the
                // paths that are going to be removed. These paths are
                // implicitly removed as a result of removing the paths in
                // toRemove
                int rCount = toRemove.size();
                for (int counter = paths.length - 1; counter >= 0; counter--) {
                    if (paths[counter] != null) {
                        for (int rCounter = rCount - 1; rCounter >= 0;
                             rCounter--) {
                            if (((TreePath)toRemove.get(rCounter)).
                                           isDescendant(paths[counter])) {
                                paths[counter] = null;
                            }
                        }
                    }
                }

                // Sort the siblings based on position in the model
                if (rCount > 1) {
                    Collections.sort(toRemove, new PositionComparator());
                }
                int[] indices = new int[rCount];
                Object[] removedNodes = new Object[rCount];
                for (int counter = rCount - 1; counter >= 0; counter--) {
                    removedNodes[counter] = ((TreePath)toRemove.get(counter)).
                                getLastPathComponent();
                    indices[counter] = treeModel.getIndexOfChild
                                        (parentNode, removedNodes[counter]);
                    parentNode.remove(indices[counter]);
                }
                treeModel.nodesWereRemoved(parentNode, indices, removedNodes);
            }
        }

        /**
         * Returns the TreePath with the smallest path count in
         * <code>paths</code>. Will return null if there is no non-null
         * TreePath is <code>paths</code>.
         */
        private TreePath findShallowestPath(TreePath[] paths) {
            int shallowest = -1;
            TreePath shallowestPath = null;

            for (int counter = paths.length - 1; counter >= 0; counter--) {
                if (paths[counter] != null) {
                    if (shallowest != -1) {
                        if (paths[counter].getPathCount() < shallowest) {
                            shallowest = paths[counter].getPathCount();
                            shallowestPath = paths[counter];
                            if (shallowest == 1) {
                                return shallowestPath;
                            }
                        }
                    }
                    else {
                        shallowestPath = paths[counter];
                        shallowest = paths[counter].getPathCount();
                    }
                }
            }
            return shallowestPath;
        }


        /**
         * An Comparator that bases the return value on the index of the
         * passed in objects in the TreeModel.
         * <p>
         * This is actually rather expensive, it would be more efficient
         * to extract the indices and then do the comparision.
         */
        private class PositionComparator implements Comparator {
            public int compare(Object o1, Object o2) {
                TreePath p1 = (TreePath)o1;
                int o1Index = treeModel.getIndexOfChild(p1.getParentPath().
                          getLastPathComponent(), p1.getLastPathComponent());
                TreePath p2 = (TreePath)o2;
                int o2Index = treeModel.getIndexOfChild(p2.getParentPath().
                          getLastPathComponent(), p2.getLastPathComponent());
                return o1Index - o2Index;
            }

            public boolean equals(Object obj) {
                return super.equals(obj);
            }
        }

    } // End of SampleTree.RemoveAction


    /**
      * ShowHandlesChangeListener implements the ChangeListener interface
      * to toggle the state of showing the handles in the tree.
      */
    class ShowHandlesChangeListener extends Object implements ChangeListener
    {
	public void stateChanged(ChangeEvent e) {
	    tree.setShowsRootHandles(((JCheckBox)e.getSource()).isSelected());
	}

    } // End of class SampleTree.ShowHandlesChangeListener


    /**
      * ShowRootChangeListener implements the ChangeListener interface
      * to toggle the state of showing the root node in the tree.
      */
    class ShowRootChangeListener extends Object implements ChangeListener
    {
	public void stateChanged(ChangeEvent e) {
	    tree.setRootVisible(((JCheckBox)e.getSource()).isSelected());
	}

    } // End of class SampleTree.ShowRootChangeListener


    /**
      * TreeEditableChangeListener implements the ChangeListener interface
      * to toggle between allowing editing and now allowing editing in
      * the tree.
      */
    class TreeEditableChangeListener extends Object implements ChangeListener
    {
	public void stateChanged(ChangeEvent e) {
	    tree.setEditable(((JCheckBox)e.getSource()).isSelected());
	}

    } // End of class SampleTree.TreeEditableChangeListener


    static public void main(String args[]) {
	new SampleTree();
    }

}