《Java2图形设计卷II：Swing》配套光盘源码

				import javax.swing.*;
				import javax.swing.event.*;
				import javax.swing.tree.*;
				import java.awt.*;
				import java.awt.event.*;
				
				public class Test extends JFrame { 
					public Test() { 
						JTree tree = new JTree();
						getContentPane().add(tree);
				
						tree.addTreeWillExpandListener(
													new TreeWillExpandListener() {
							public void treeWillExpand(TreeExpansionEvent e) 
													  throws ExpandVetoException {
								TreePath path = e.getPath();
								TreeNode node = (TreeNode)
												path.getLastPathComponent();
				
								if(node.toString().equals("colors")) {
									JOptionPane.showMessageDialog(Test.this,
												"Can't Expand Colors",
												"Expansion Vetoed",
												JOptionPane.INFORMATION_MESSAGE);
				
									throw new ExpandVetoException(e); 
								}
							}
							public void treeWillCollapse(TreeExpansionEvent e) 
													  throws ExpandVetoException {
								TreePath path = e.getPath();
								TreeNode node = (TreeNode)
												path.getLastPathComponent();
				
								if(node.toString().equals("food")) {
									JOptionPane.showMessageDialog(Test.this,
												"Can't Collapse Food",
												"Collapse Vetoed",
												JOptionPane.INFORMATION_MESSAGE);
				
									throw new ExpandVetoException(e); 
								}
							}
						});
					}
					public static void main(String args[]) {
						GraphicJavaApplication.launch(new Test(), 
							"Vetoing Node Expansion/Collapse",300,300,300,200);
					}
				}
				class GraphicJavaApplication extends WindowAdapter {
					public static void launch(final JFrame f, String title,
											  final int x, final int y, 
											  final int w, int h) {
						f.setTitle(title);
						f.setBounds(x,y,w,h);
						f.setVisible(true);
				
						f.setDefaultCloseOperation(
											WindowConstants.DISPOSE_ON_CLOSE);
				
						f.addWindowListener(new WindowAdapter() {
							public void windowClosed(WindowEvent e) {
								System.exit(0);
							}
						});
					}
				}