JTree expansion & collapse programatically

[Nageswar Kakolla]

Hi there,

I am trying to do JTree expand & collapse one level at a time whenever user presses Expand & collapse button.

few questins ?

there are so many implementations if found for above way using getRowcount,
getRootToPaht(rootNode) and expand recursively etc

while expand is working , collapse wont work if both are implemented using same logic

Also, JTree.getRowCount() API returns no. of rows ? I dont understand this
JTree is stored as row & columns in array and does some body can explain this that will be great ?

int row = m_deficiencyTree.getRowCount();

while(row >= 0){
m_deficiencyTree.collapseRow(row);
row--;
}

above code is for whole Tree collapse but i want to do one at a time ?
similary with Tree expansion ?

Also, Swing is becoming tougher for me since it looks like i have to master API or what is better way to mast SWING

[Craig Wood]

import java.awt.*;
import java.awt.event.*;
import java.util.Enumeration;
import javax.swing.*;
import javax.swing.tree.*;
 
public class TreeExpansion implements ActionListener
{
    JTree tree;
 
    public void actionPerformed(ActionEvent e)
    {
        JButton button = (JButton)e.getSource();
        String ac = button.getActionCommand();
        if(ac.equals("expand"))
        {
            DefaultMutableTreeNode node = getLastExpandableNode();
            setExpandedState((String)node.getUserObject(), true);
        }
        if(ac.equals("collapse"))
        {
            DefaultMutableTreeNode node = getFirstCollapsableNode();
            setExpandedState((String)node.getUserObject(), false);
        }
    }
 
    private DefaultMutableTreeNode getFirstCollapsableNode()
    {
        DefaultMutableTreeNode root =
                (DefaultMutableTreeNode)tree.getModel().getRoot();
        Enumeration e = root.depthFirstEnumeration();
        while(e.hasMoreElements())
        {
            DefaultMutableTreeNode n = (DefaultMutableTreeNode)e.nextElement();
            if(n.getChildCount() > 0 && tree.isExpanded(new TreePath(n.getPath())))
                return n;
        }
        return root;
    }
 
    private DefaultMutableTreeNode getLastExpandableNode()
    {
        DefaultMutableTreeNode root =
                (DefaultMutableTreeNode)tree.getModel().getRoot();
        DefaultMutableTreeNode lastNode = root;
        Enumeration e = root.depthFirstEnumeration();
        while(e.hasMoreElements())
        {
            DefaultMutableTreeNode n = (DefaultMutableTreeNode)e.nextElement();
            if(n.getChildCount() > 0 && n.getDepth() == 1 &&
                      !tree.isExpanded(new TreePath(n.getPath())))
                lastNode = n;
        }
        return lastNode;
    }
 
    private void setExpandedState(String id, boolean expand)
    {
        DefaultMutableTreeNode root = (DefaultMutableTreeNode)tree.getModel().getRoot();
        Enumeration e = root.breadthFirstEnumeration();
        while(e.hasMoreElements())
        {
            DefaultMutableTreeNode node = (DefaultMutableTreeNode)e.nextElement();
            if(node.getUserObject().equals(id))
            {
                TreePath path = new TreePath(node.getPath());
                expandNode(path, expand);
                break;
            }
        }
    }
 
    private void expandNode(TreePath parent, boolean expand)
    {
        TreeNode node = (TreeNode)parent.getLastPathComponent();
        if (node.getChildCount() >= 0)
        {
            Enumeration e = node.children();
            while(e.hasMoreElements())
            {
                TreeNode n = (TreeNode)e.nextElement();
                TreePath path = parent.pathByAddingChild(n);
                expandNode(path, expand);
            }
        }
        if(expand)
            tree.expandPath(parent);
        else
            tree.collapsePath(parent);
    }
 
    private JTree getTree()
    {
        DefaultMutableTreeNode
            root = new DefaultMutableTreeNode("root"),
            leaf;
        DefaultMutableTreeNode[]
            nodes    = new DefaultMutableTreeNode[3],
            subNodes = new DefaultMutableTreeNode[8];
        int[][] keys = {  { 1, 2, 3 }, { 3 }, { 1, 2, 3, 4 }  };
        int subIndex = 0;
        for(int j = 0; j < nodes.length; j++)
        {
            nodes[j] = new DefaultMutableTreeNode("node " + (j+1));
            root.insert(nodes[j], j);
            for(int k = 0; k < keys[j].length; k++, subIndex++)
            {
                String id = "sub " + (j+1) + (k+1);
                subNodes[subIndex] = new DefaultMutableTreeNode(id);
                nodes[j].insert(subNodes[subIndex], k);
                for(int m = 0; m < keys[j][k]; m++)
                {
                    id = "leaf " + (j+1) + (k+1) + (m+1);
                    leaf = new DefaultMutableTreeNode(id);
                    subNodes[subIndex].insert(leaf, m);
                    if(j == 1 && k == 0 && m == 1)
                    {
                        DefaultMutableTreeNode n = new DefaultMutableTreeNode("2121");
                        leaf.insert(n, 0);
                        DefaultMutableTreeNode p = new DefaultMutableTreeNode("21211");
                        n.insert(p, 0);
                    }
                }
            }
        }
        DefaultTreeModel model = new DefaultTreeModel(root);
        tree = new JTree(model);
        return tree;
    }
 
    private Box getControls()
    {
        JButton collapse = new JButton("collapse");
        JButton expand = new JButton("expand");
        collapse.setActionCommand("collapse");
        expand.setActionCommand("expand");
        collapse.addActionListener(this);
        expand.addActionListener(this);
        Box box = Box.createHorizontalBox();
        box.add(Box.createHorizontalGlue());
        box.add(collapse);
        box.add(Box.createHorizontalGlue());
        box.add(expand);
        box.add(Box.createHorizontalGlue());
        return box;
    }
 
    public static void main(String[] args)
    {
        TreeExpansion test = new TreeExpansion();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new JScrollPane(test.getTree()));
        f.getContentPane().add(test.getControls(), "South");
        f.setSize(400,400);
        f.setLocation(575,200);
        f.setVisible(true);
    }
}