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JTextArea as JTree node label

Posted on 2004-10-26
Medium Priority
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
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LVL 86

Expert Comment

ID: 12413968
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

ID: 12415144
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

ID: 12415228
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 ???

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LVL 92

Expert Comment

ID: 12416644
You need to create a TreeCellEditor, as well as a TreeCellRenderer.
LVL 92

Accepted Solution

objects earned 2000 total points
ID: 12417570

Expert Comment

ID: 12418651
objects referenced website is fine. go there and download that java file.

Author Comment

ID: 12427035
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

ID: 12427958

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