JTextArea as JTree node label

Posted on 2004-10-26
Last Modified: 2012-06-27

I want my JTree to display a JTextArea as its node label.
For example:
When a node minimizes, only the 1st line of the text string is shown.
When a node expandes, the entire multi-line text string is shown.
It would look this:

Root +----LABEL A line 1
        |     LABEL A line 2
        |     .....
        +----LABEL B Line 1

I try extending javax.swing.tree.DefaultTreeCellRenderer
but I could not get it to display a JTextArea as the node label.

How should I approach this problem ?

Is there any sample source code out there ?

Any commercial UI javabean that can do this ?

I would appreciate any comment or suggestion.

Question by:csunlistek
    LVL 86

    Expert Comment

    I try extending javax.swing.tree.DefaultTreeCellRenderer
    but I could not get it to display a JTextArea as the node label.

    Can you post your code?


    Author Comment

    Yes, here is my latest test code. tested under JDK 1.4.2.
    It implements TreeCellRenderer.
    It was at least able to display a JTextArea as a tree node
    but it has the following problems:

    1. resizing. How do I get the width of JTextArea to fit the width of the frame ?
    2. border. How do I draw the border around JTextArea to show the boundary of text ?

    Thanks for any suggestion.  sample code would be useful.


    package test;

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

    public class MyJTree extends JPanel {

      public MyJTree() {
        setLayout(new BorderLayout());
        // init data model
        String dummyText="";
        for (int i = 0; i < 10; i++) dummyText +=" ABCDE"; // dummy text string
        //for (int i = 0; i < 10; i++) dummyText +=" ABCDE \n"; // shows multiline here
        DefaultMutableTreeNode root =  new DefaultMutableTreeNode("root");
        for (int i = 0; i < 3; i++) {
          DefaultMutableTreeNode child = new DefaultMutableTreeNode("Child "+i + dummyText);
          root.add( child );
          for (int  j= 0; j < 3; j++)
            child.add( new DefaultMutableTreeNode("GrandChild "+i+"."+ j + dummyText));
        DefaultTreeModel model = new DefaultTreeModel(root);
        // create tree UI
        JTree tree = new JTree(model);
         // Change the cell renderer
         tree.setCellRenderer(new CellRenderer());
         // Put tree in a scrollable pane
         JScrollPane sp = new JScrollPane(tree);
         add(sp, BorderLayout.CENTER);

      // my cell renderer
     class CellRenderer implements TreeCellRenderer {
          JTextArea renderer;

          CellRenderer () {
            renderer = new JTextArea();
            renderer.setOpaque (true);

          public Component  getTreeCellRendererComponent(JTree tree,
              Object value, boolean selected, boolean expanded,
              boolean leaf, int row, boolean hasFocus) {

            // Change background color based on selected state
            Color background = (selected ? Color.lightGray : Color.white);

            String text = value.toString();

            if (expanded) { // in expanded state, display all text
              renderer.setPreferredSize(new Dimension(200,80));
            } else { // in minimized state, display 1st 10 chars
              renderer.setText( (text.length()>10 ?  text.substring(0, 10) : text) );
              renderer.setPreferredSize(new Dimension(200,20));
            return renderer;

        public static void main(String[] args) {
          MyJTree t = new MyJTree();
          JFrame frame = new JFrame();
          frame.setSize(300, 300);


    Author Comment

    One more question to add to above:

    3. Editing. How do I make the JTextArea as tree node editable ?
    It appears the CellRenderer approach is designed for display text, not for in-place text editing.

    Maybe I approach the whole problem in the wrong way ???

    LVL 92

    Expert Comment

    You need to create a TreeCellEditor, as well as a TreeCellRenderer.
    LVL 92

    Expert Comment

    LVL 92

    Accepted Solution

    LVL 5

    Expert Comment

    objects referenced website is fine. go there and download that java file.

    Author Comment

    The sample codes do not work exactly as I had in mind (editing, border, auto JTextArea width adjustment, line wrap, etc) but they provide a good starting point, enough to get me going again.

    Thanks for all the help.
    LVL 92

    Expert Comment


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