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JTree Clicking problem

1 reply on 1 page. Most recent reply: Mar 17, 2002 4:10 PM by Matt Gerrans

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Lois

Posts: 4
Nickname: lois
Registered: Mar, 2002

JTree Clicking problem

Posted: Mar 17, 2002 4:06 PM

Hi, I need to implement a JTree that loads its children only upon clicking the node. Everything was fine until when I tried to click the icon to expand and collapse, some runtime error (NullPointerException) appears. Is clicking the + icon and double clicking the folder icon in order to expand/collapse the path not the same? Appended is the code. Thanks....sorry, sorta long. Any comment is welcome.

import javax.swing.*;
import javax.swing.tree.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.event.*;
import java.io.*;

public class TreeGUI implements TreeSelectionListener
{
private Controller ct;
private String root;

private ExtendNode rootNode;

private JTree tree;
private DefaultTreeModel tree_model;
private JScrollPane sp;

private ArrayList isExpanded;

public TreeGUI(Controller controller, String rootString) {
//System.out.println("AAAAAAAAAAAAAAAA");
isExpanded = new ArrayList();
ct = controller;
rootNode = buildNode(rootString, rootString);

tree_model = new DefaultTreeModel(rootNode);

tree = new JTree(tree_model);
tree.putClientProperty("JTree.lineStyle", "Angled");
sp = new JScrollPane(tree);
sp.setPreferredSize(new Dimension(500,600));
ct.add(sp);
tree.addTreeSelectionListener(this);
buildTree(rootNode);

}

public void valueChanged(TreeSelectionEvent e) {
System.out.println("\nBBBBBBBBBBBBBBBB");
ExtendNode temp = (ExtendNode)tree.getLastSelectedPathComponent();
//buildTree(temp);
ct.NodeClicked(temp);
//tree.expandPath(new TreePath(temp.getPath()));

}

public String fullPath(ExtendNode node) {
System.out.println("CCCCCCCCCCCCCCCCCCC");
TreeNode[] tn = node.getPath();
String str="";
for (int i=0; i<tn.length; i++)
str += tn.toString() + "\\";
str = str.substring(0, str.length()-1);

if (isExpanded.contains(str)) {
System.out.println("Already contains : " + str);
return null;
}
else {
System.out.println("First time contains : " + str);
isExpanded.add(str);
return str;
}
}

public void buildTree(ExtendNode parentNode) {
System.out.println("11111111111111");

String temp = fullPath(parentNode);

if (temp == null) {
System.out.println("2222222222222");
System.out.println("file is null");
return;
}
else {
System.out.println("3333333333333333");
File file = new File(temp);
if (file.isDirectory()) {
System.out.println("44444444444444444");
String[] childFiles = file.list();
Arrays.sort(childFiles);
for (int i=0; i<childFiles.length; i++) {
System.out.println("55555555555555555");
System.out.println("ChildFiles : " + childFiles.toString());
ExtendNode childNode = buildNode(childFiles, temp + '\\' + childFiles);
tree_model.insertNodeInto(childNode, parentNode,0);
}
}
else {
System.out.println("666666666666");
return;
}
}
}

public ExtendNode buildNode(String node, String absPath) {
System.out.println("EEEEEEEEEEEEEEEEEEE");
System.out.println("Node : " + node);
File file = new File(absPath);

if (file.isDirectory()) {
return new ExtendNode(node, false);
}
else
return new ExtendNode(node, true);
}
}

import javax.swing.*;
import java.awt.*;
import javax.swing.tree.*;

public class ExtendNode extends DefaultMutableTreeNode {

private boolean leaf;

public ExtendNode(String arg, boolean leaf) {
super(arg);
this.leaf = leaf;
}

public boolean isLeaf() {
return leaf;
}

}

Matt Gerrans

Posts: 1153
Nickname: matt
Registered: Feb, 2002

Re: JTree Clicking problem

Posted: Mar 17, 2002 4:10 PM

Quick comment, before I've looked very closely: Please use the java formatting tags mentioned in "Formatting Your Post" at the bottom of the page!

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