Help with building a JTree using tree node and node renderers

Question

Hi,
I am having a few problems with JTree's. basically I want to build JTree from a web spider. The webspide searches a website checking links and stores the current url that is being processed as a string in the variable msg. I wan to use this variable to build a JTree in a new class and then add it to my GUI. I have created a tree node class and a renderer node class, these classes are built fine. can someone point me in the direction for actually using these to build my tree in a seperate class and then displaying it in a GUI class?
*nodeRenderer.java
import javax.swing.*;
import javax.swing.tree.*;
import java.awt.*;
import java.net.*;
public class nodeRenderer extends DefaultTreeCellRenderer
                                   implements TreeCellRenderer
public static Icon icon= null;
public nodeRenderer() {
icon = new ImageIcon(getClass().getResource("icon.gif"));
public Component getTreeCellRendererComponent(
JTree tree,
Object value,
boolean sel,
boolean expanded,
boolean leaf,
int row,
boolean hasFocus) {
super.getTreeCellRendererComponent(
tree, value, sel,
expanded, leaf, row,
hasFocus);
treeNode node = (treeNode)(((DefaultMutableTreeNode)value).getUserObject());
if(icon != null) // set a custom icon
setOpenIcon(icon);
setClosedIcon(icon);
setLeafIcon(icon);
     return this;
*treeNode.java
*this is the class to represent a node
import javax.swing.*;
import javax.swing.tree.*;
import java.util.*;
import java.net.*;
* Class used to hold information about a web site that has
* been searched by the spider class
public class treeNode
*Url from the WebSpiderController Class
*that is currently being processed
public String msg;
treeNode(String urlText)
     msg = urlText;
String getUrlText()
     return msg;
//gui.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import java.net.*;
import java.io.*;
import java.util.*;
public class gui extends JFrame implements Runnable
     *declare variable, boolean
     *thread, a object and a center
     *pane
     protected URL urlInput;
     protected Thread bgThread;
     protected boolean run = false;
     protected WebSpider webSpider;
     public gui()
          *create the gui here
          setTitle("Testing Tool");
     setSize(600,600);
     //add Buttons to the tool bar
     start.setText("Start");
     start.setActionCommand("Start");
     toolBar.add(start);
     ButtonListener startListener = new ButtonListener();
          start.addActionListener(startListener);
          cancel.setText("Cancel");
     cancel.setActionCommand("Cancel");
     toolBar.add(cancel);
     ButtonListener cancelListener = new ButtonListener();
          cancel.addActionListener(cancelListener);
          close.setText("Close");
     close.setActionCommand("Close");
     toolBar.add(close);
     ButtonListener closeListener = new ButtonListener();
          close.addActionListener(closeListener);
          //creat a simple form
          urlLabel.setText("Enter URL:");
          urlLabel.setBounds(100,36,288,24);
          formTab.add(urlLabel);
          url.setBounds(170,36,288,24);
          formTab.add(url);
          current.setText("Currently Processing: ");
          current.setBounds(100,80,288,24);
          formTab.add(current);
     //add scroll bars to the error messages screen and website structure
     errorPane.setAutoscrolls(true);
     errorPane.setHorizontalScrollBarPolicy(javax.swing.
     ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
     errorPane.setVerticalScrollBarPolicy(javax.swing.
     ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
     errorPane.setOpaque(true);
     errorTab.add(errorPane);
     errorPane.setBounds(0,0,580,490);
     errorText.setEditable(false);
     errorPane.getViewport().add(errorText);
     errorText.setBounds(0,0,600,550);
     treePane.setAutoscrolls(true);
     treePane.setHorizontalScrollBarPolicy(javax.swing.
     ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
     treePane.setVerticalScrollBarPolicy(javax.swing.
     ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
     treePane.setOpaque(true);
     treeTab.add(treePane);
     treePane.setBounds(0,0,580,490);
     treeText.setEditable(false);
     treePane.getViewport().add(treeText);
     treeText.setBounds(0,0,600,550);
     //create the tabbed window           
centerPane.setBorder(new javax.swing.border.EtchedBorder());
formTab.setLayout(null);
errorTab.setLayout(null);
treeTab.setLayout(null);
centerPane.addTab("Search Parameters", formTab);
centerPane.addTab("Error Messages", errorTab);
centerPane.addTab("Website Structure", treeTab);
          //add the tool bar and tabbed pane
          getContentPane().add(toolBar, java.awt.BorderLayout.NORTH);
getContentPane().add(centerPane, java.awt.BorderLayout.CENTER);                    
          *create the tool bar pane, a center pane, add the buttons,
          *labels, tabs, a text field for user input here
          javax.swing.JPanel toolBar = new javax.swing.JPanel();
          javax.swing.JButton start = new javax.swing.JButton();
          javax.swing.JButton cancel = new javax.swing.JButton();
          javax.swing.JButton close = new javax.swing.JButton();      
          javax.swing.JTabbedPane centerPane = new javax.swing.JTabbedPane();
          javax.swing.JPanel formTab = new javax.swing.JPanel();
          javax.swing.JLabel urlLabel = new javax.swing.JLabel();
          javax.swing.JLabel current = new javax.swing.JLabel();
          javax.swing.JTextField url = new javax.swing.JTextField();
          javax.swing.JPanel errorTab = new javax.swing.JPanel();
          javax.swing.JTextArea errorText = new javax.swing.JTextArea();
          javax.swing.JScrollPane errorPane = new javax.swing.JScrollPane();
          javax.swing.JPanel treeTab = new javax.swing.JPanel();
          javax.swing.JTextArea treeText = new javax.swing.JTextArea();
          javax.swing.JScrollPane treePane = new javax.swing.JScrollPane();
          javax.swing.JTree searchTree = new javax.swing.JTree();
          *show the gui
          public static void main(String args[])
          (new gui()).setVisible(true);
     *listen for the button presses and set the
     *boolean flag depending on which button is pressed
     class ButtonListener implements ActionListener
          public void actionPerformed(ActionEvent event)
               Object object = event.getSource();
               if (object == start)
                    run = true;
                    startActionPerformed(event);
               if (object == cancel)
                    run = false;
                    startActionPerformed(event);
               if (object == close)
                    System.exit(0);
     *this method is called when the start or
     *cancel button is pressed.
     void startActionPerformed (ActionEvent event)
          if (run == true && bgThread == null)
               bgThread = new Thread(this);
               bgThread.start();
          if (run == false && bgThread != null)
               webSpider.cancel();
     *this mehtod will start the background thred.
     *the background thread is required so that the
     *GUI is still displayed
     public void run()
          try
               webSpider = new WebSpider(this);
               webSpider.clear();
               urlInput = new URL(url.getText());
               webSpider.addURL(urlInput);
               webSpider.run();
               bgThread=null;
          catch (MalformedURLException e)
               addressError addErr = new addressError();
               addErr.addMsg = "URL ERROR - PLEASE CHECK";
               SwingUtilities.invokeLater(addErr);
          *this method is called by the web spider
          *once a url is found. Validation of navigation
          *happens here.
          public boolean urlFound(URL urlInput,URL url)
               CurrentlyProcessing pro = new CurrentlyProcessing();
          pro.msg = url.toString();
          SwingUtilities.invokeLater(pro);
          if (!testLink(url))
                    navigationError navErr = new navigationError();
                    navErr.navMsg = "Broken Link "+url+" caused on "+urlInput+"\n";
                    return false;
          if (!url.getHost().equalsIgnoreCase(urlInput.getHost()))
               return false;
          else
               return true;
          *this method is called internally to check
     *that a link works
          protected boolean testLink(URL url)
          try
               URLConnection connection = url.openConnection();
               connection.connect();
               return true;
          catch (IOException e)
               return false;
     *this method is called when an error is
     *found.
          public void URLError(URL url)
          *this method is called when an email
          *address is found
          public void emailFound(String email)
          /*this method will update any errors found inc
          *address errors and broken links
          class addressError implements Runnable
               public String addMsg;
               public void run()
                    errorText.append(addMsg);
                    current.setText("Currently Processing: "+ addMsg);
          class navigationError implements Runnable
               public String navMsg;
               public void run()
                    errorText.append(navMsg);
          *this method will update the currently
          *processing field on the GUI
          class CurrentlyProcessing implements Runnable
          public String msg;
          public void run()
               current.setText("Currently Processing: " + msg );
//webspider.java
import java.util.*;
import java.net.*;
import java.io.*;
import javax.swing.text.*;
import javax.swing.text.html.*;
import javax.swing.tree.*;
import javax.swing.*;
*this class implements the spider.
public class WebSpider extends HTMLEditorKit
     *make a collection of the URL's
     protected Collection urlErrors = new ArrayList(3);
     protected Collection urlsWaiting = new ArrayList(3);
     protected Collection urlsProcessed = new ArrayList(3);
     //report URL's to this class
     protected gui report;
     *this flag will indicate whether the process
     *is to be cancelled
     protected boolean cancel = false;
     *The constructor
     *report the urls to the wui class
     public WebSpider(gui report)
     this.report = report;
     *get the urls from the above declared
     *collections
     public Collection getUrlErrors()
     return urlErrors;
     public Collection getUrlsWaiting()
     return urlsWaiting;
     public Collection getUrlsProcessed()
     return urlsProcessed;
     * Clear all of the collections.
     public void clear()
     getUrlErrors().clear();
     getUrlsWaiting().clear();
     getUrlsProcessed().clear();
     *Set a flag that will cause the begin
     *method to return before it is done.
     public void cancel()
     cancel = true;
     *add the entered url for porcessing
     public void addURL(URL url)
     if (getUrlsWaiting().contains(url))
          return;
     if (getUrlErrors().contains(url))
          return;
     if (getUrlsProcessed().contains(url))
          return;
     /*WRITE TO LOG FILE*/
     log("Adding to workload: " + url );
     getUrlsWaiting().add(url);
     *process a url
     public void processURL(URL url)
     try
          /*WRITE TO LOGFILE*/
          log("Processing: " + url );
          // get the URL's contents
          URLConnection connection = url.openConnection();
          if ((connection.getContentType()!=null) &&
     !connection.getContentType().toLowerCase().startsWith("text/"))
          getUrlsWaiting().remove(url);
          getUrlsProcessed().add(url);
          log("Not processing because content type is: " +
     connection.getContentType() );
               return;
     // read the URL
     InputStream is = connection.getInputStream();
     Reader r = new InputStreamReader(is);
     // parse the URL
     HTMLEditorKit.Parser parse = new HTMLParse().getParser();
     parse.parse(r,new Parser(url),true);
catch (IOException e)
     getUrlsWaiting().remove(url);
     getUrlErrors().add(url);
     log("Error: " + url );
     report.URLError(url);
     return;
// mark URL as complete
getUrlsWaiting().remove(url);
getUrlsProcessed().add(url);
log("Complete: " + url );
*start the spider
public void run()
cancel = false;
while (!getUrlsWaiting().isEmpty() && !cancel)
     Object list[] = getUrlsWaiting().toArray();
     for (int i=0;(i<list.length)&&!cancel;i++)
     processURL((URL)list);
* A HTML parser callback used by this class to detect links
protected class Parser extends HTMLEditorKit.ParserCallback
protected URL urlInput;
public Parser(URL urlInput)
this.urlInput = urlInput;
public void handleSimpleTag(HTML.Tag t,MutableAttributeSet a,int pos)
String href = (String)a.getAttribute(HTML.Attribute.HREF);
if((href==null) && (t==HTML.Tag.FRAME))
href = (String)a.getAttribute(HTML.Attribute.SRC);
if (href==null)
return;
int i = href.indexOf('#');
if (i!=-1)
href = href.substring(0,i);
if (href.toLowerCase().startsWith("mailto:"))
report.emailFound(href);
return;
handleLink(urlInput,href);
public void handleStartTag(HTML.Tag t,MutableAttributeSet a,int pos)
handleSimpleTag(t,a,pos); // handle the same way
protected void handleLink(URL urlInput,String str)
try
     URL url = new URL(urlInput,str);
if (report.urlFound(urlInput,url))
addURL(url);
catch (MalformedURLException e)
log("Found malformed URL: " + str);
*log the information of the spider
public void log(String entry)
System.out.println( (new Date()) + ":" + entry );
I have a seperate class for parseing the HTML. Any help would be greatly appreciated
mrv

Answer 1

Hi Sorry to be a pain again,
I have re worked the gui class so it looks like this now:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.net.*;
import java.io.*;
import java.util.*;
public class gui extends JFrame implements Runnable
     *declare variable, boolean
     *thread, a object and a center
     *pane
     protected URL urlInput;
     protected Thread bgThread;
     protected boolean run = false;
     protected WebSpider webSpider;
     public String msgInfo;
     public String brokenUrl;
     public String goodUrl;
     public String deadUrl;
     protected DefaultMutableTreeNode rootNode;
protected DefaultTreeModel treeModel;
     public gui()
          *create the gui here
          setTitle("Testing Tool");
     setSize(600,600);
     //add Buttons to the tool bar
     start.setText("Start");
     start.setActionCommand("Start");
     toolBar.add(start);
     ButtonListener startListener = new ButtonListener();
          start.addActionListener(startListener);
          cancel.setText("Cancel");
     cancel.setActionCommand("Cancel");
     toolBar.add(cancel);
     ButtonListener cancelListener = new ButtonListener();
          cancel.addActionListener(cancelListener);
          close.setText("Close");
     close.setActionCommand("Close");
     toolBar.add(close);
     ButtonListener closeListener = new ButtonListener();
          close.addActionListener(closeListener);
          //creat a simple form
          urlLabel.setText("Enter URL:");
          urlLabel.setBounds(100,36,288,24);
          formTab.add(urlLabel);
          url.setBounds(170,36,288,24);
          formTab.add(url);
          current.setText("Currently Processing: ");
          current.setBounds(100,80,288,24);
          formTab.add(current);
     //add scroll bars to the error messages screen and website structure
     errorPane.setAutoscrolls(true);
     errorPane.setHorizontalScrollBarPolicy(javax.swing.
     ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
     errorPane.setVerticalScrollBarPolicy(javax.swing.
     ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
     errorPane.setOpaque(true);
     errorTab.add(errorPane);
     errorPane.setBounds(0,0,580,490);
     errorText.setEditable(false);
     errorPane.getViewport().add(errorText);
     errorText.setBounds(0,0,600,550);
     treePane.setAutoscrolls(true);
     treePane.setHorizontalScrollBarPolicy(javax.swing.
     ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
     treePane.setVerticalScrollBarPolicy(javax.swing.
     ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
     treePane.setOpaque(true);
     treeTab.add(treePane);
     treePane.setBounds(0,0,580,490);
     treeText.setEditable(false);
     treePane.getViewport().add(treeText);
     treeText.setBounds(0,0,600,550);
     //JTree
     // NEW CODE
     rootNode = new DefaultMutableTreeNode("Root Node");
     treeModel = new DefaultTreeModel(rootNode);
     treeModel.addTreeModelListener(new MyTreeModelListener());
     tree = new JTree(treeModel);
     tree.setEditable(true);
     tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
tree.setShowsRootHandles(true);
     treeText.add(tree);
     //create the tabbed window           
centerPane.setBorder(new javax.swing.border.EtchedBorder());
formTab.setLayout(null);
errorTab.setLayout(null);
treeTab.setLayout(null);
centerPane.addTab("Search Parameters", formTab);
centerPane.addTab("Error Messages", errorTab);
centerPane.addTab("Website Structure", treeTab);
          //add the tool bar and tabbed pane
          getContentPane().add(toolBar, java.awt.BorderLayout.NORTH);
getContentPane().add(centerPane, java.awt.BorderLayout.CENTER);     
          *create the tool bar pane, a center pane, add the buttons,
          *labels, tabs, a text field for user input here
          javax.swing.JPanel toolBar = new javax.swing.JPanel();
          javax.swing.JButton start = new javax.swing.JButton();
          javax.swing.JButton cancel = new javax.swing.JButton();
          javax.swing.JButton close = new javax.swing.JButton();      
          javax.swing.JTabbedPane centerPane = new javax.swing.JTabbedPane();
          javax.swing.JPanel formTab = new javax.swing.JPanel();
          javax.swing.JLabel urlLabel = new javax.swing.JLabel();
          javax.swing.JLabel current = new javax.swing.JLabel();
          javax.swing.JTextField url = new javax.swing.JTextField();
          javax.swing.JPanel errorTab = new javax.swing.JPanel();
          javax.swing.JTextArea errorText = new javax.swing.JTextArea();
          javax.swing.JScrollPane errorPane = new javax.swing.JScrollPane();
          javax.swing.JPanel treeTab = new javax.swing.JPanel();
          javax.swing.JTextArea treeText = new javax.swing.JTextArea();
          javax.swing.JScrollPane treePane = new javax.swing.JScrollPane();
          javax.swing.JTree tree = new javax.swing.JTree();
          *show the gui
          public static void main(String args[])
          (new gui()).setVisible(true);
     *listen for the button presses and set the
     *boolean flag depending on which button is pressed
     class ButtonListener implements ActionListener
          public void actionPerformed(ActionEvent event)
               Object object = event.getSource();
               if (object == start)
                    run = true;
                    startActionPerformed(event);
               if (object == cancel)
                    run = false;
                    startActionPerformed(event);
               if (object == close)
                    System.exit(0);
     *this method is called when the start or
     *cancel button is pressed.
     void startActionPerformed (ActionEvent event)
          if (run == true && bgThread == null)
               bgThread = new Thread(this);
               bgThread.start();
               //new line of code
               treeText.addObject(msgInfo);
          if (run == false && bgThread != null)
               webSpider.cancel();
     *this mehtod will start the background thred.
     *the background thread is required so that the
     *GUI is still displayed
     public void run()
          try
               webSpider = new WebSpider(this);
               webSpider.clear();
               urlInput = new URL(url.getText());
               webSpider.addURL(urlInput);
               webSpider.run();
               bgThread = null;
          catch (MalformedURLException e)
               addressError addErr = new addressError();
               addErr.addMsg = "URL ERROR - PLEASE CHECK";
               SwingUtilities.invokeLater(addErr);
          *this method is called by the web spider
          *once a url is found. Validation of navigation
          *happens here.
          public boolean urlFound(URL urlInput,URL url)
               CurrentlyProcessing pro = new CurrentlyProcessing();
          pro.msg = url.toString();
          SwingUtilities.invokeLater(pro);
          if (!testLink(url))
                    navigationError navErr = new navigationError();
                    navErr.navMsg = "Broken Link "+url+" caused on "+urlInput+"\n";
                    brokenUrl = url.toString();
                    return false;
          if (!url.getHost().equalsIgnoreCase(urlInput.getHost()))
               return false;
          else
               return true;
          *this method is returned if there is no link
          *on a web page, e.g. there us a dead end
          public void urlNotFound(URL urlInput)
                    deadEnd dEnd = new deadEnd();
                    dEnd.dEMsg = "No links on "+urlInput+"\n";
                    deadUrl = urlInput.toString();               
          *this method is called internally to check
     *that a link works
          protected boolean testLink(URL url)
          try
               URLConnection connection = url.openConnection();
               connection.connect();
               goodUrl = url.toString();
               return true;
          catch (IOException e)
               return false;
     *this method is called when an error is
     *found.
          public void urlError(URL url)
          *this method is called when an email
          *address is found
          public void emailFound(String email)
          /*this method will update any errors found inc
          *address errors and broken links
          class addressError implements Runnable
               public String addMsg;
               public void run()
                    current.setText("Currently Processing: "+ addMsg);
                    errorText.append(addMsg);
          class navigationError implements Runnable
               public String navMsg;
               public void run()
                    errorText.append(navMsg);
          class deadEnd implements Runnable
               public String dEMsg;
               public void run()
                    errorText.append(dEMsg);
          *this method will update the currently
          *processing field on the GUI
          public class CurrentlyProcessing implements Runnable
               public String msg;
          //new line
          public String msgInfo = msg;
          public void run()
               current.setText("Currently Processing: " + msg );
     * NEW CODE
     * NEED THIS CODE SOMEWHERE
     * treeText.addObject(msgInfo);
     public DefaultMutableTreeNode addObject(Object child)
     DefaultMutableTreeNode parentNode = null;
     TreePath parentPath = tree.getSelectionPath();
     if (parentPath == null)
     parentNode = rootNode;
     else
     parentNode = (DefaultMutableTreeNode)
(parentPath.getLastPathComponent());
     return addObject(parentNode, child, true);
     public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,
Object child)
     return addObject(parent, child, false);
     public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,
     Object child,boolean shouldBeVisible)
     DefaultMutableTreeNode childNode = new DefaultMutableTreeNode(child);
     if (parent == null)
     parent = rootNode;
     treeModel.insertNodeInto(childNode, parent, parent.getChildCount());
     if (shouldBeVisible)
     tree.scrollPathToVisible(new TreePath(childNode.getPath()));
          return childNode;
     public class MyTreeModelListener implements TreeModelListener
          public void treeNodesChanged (TreeModelEvent e)
               DefaultMutableTreeNode node;
               node = (DefaultMutableTreeNode)
               (e.getTreePath().getLastPathComponent());
               try
                    int index = e.getChildIndices()[0];
                    node = (DefaultMutableTreeNode)
                    (node.getChildAt(index));
               catch (NullPointerException exc)
          public void treeNodesInserted(TreeModelEvent e)
          public void treeStructureChanged(TreeModelEvent e)
          public void treeNodesRemoved(TreeModelEvent e)
I beleive that this line of code is required:
treeText.addObject(msgInfo);
I have placed it where the action events start the spider, but i keep getting this error:
cannot resolve symbol
symbol : method addObject (java.lang.String)
location: class javax.swing.JTextArea
treeText.addObject(msgInfo);
Also the jtree is not showing the window that I want it to and I am not too sure why. could you have a look to see why? i think it needs a fresh pair of eyes.
Many thanks
MrV