Use UIManager to change the default icon for JTree : JTree Editor Renderer « Swing « Java Tutorial

1. Java Tutorial
2. Swing
3. JTree Editor Renderer

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.UIManager;

public class Main {
  public static void main(String[] argv) throws Exception {
    Icon leafIcon = new ImageIcon("leaf.gif");
    Icon openIcon = new ImageIcon("open.gif");
    Icon closedIcon = new ImageIcon("closed.gif");

    UIManager.put("Tree.leafIcon", leafIcon);
    UIManager.put("Tree.openIcon", openIcon);
    UIManager.put("Tree.closedIcon", closedIcon);
    
    JTree tree = new JTree();

    JFrame f = new JFrame();
    f.add(new JScrollPane(tree));
    f.setSize(300, 300);
    f.setVisible(true);

  }
}

14.69.JTree Editor Renderer
	14.69.1.	Getting Default TreeCellRenderer From JTree
	14.69.2.	extends JLabel implements TreeCellRenderer
	14.69.3.	Creating a Custom Renderer
	14.69.4.	Working with Tree Tooltips: using a Tooltip Cell Renderer
	14.69.5.	Editing Tree Nodes with triple clicking
	14.69.6.	Creating a DefaultCellEditor: JTextField
	14.69.7.	Creating a DefaultCellEditor: JComboBox
	14.69.8.	Creating a DefaultCellEditor: JCheckBox
	14.69.9.	Creating a Proper ComboBox Editor for a Tree
	14.69.10.	Creating an Editor Just for Leaf Nodes
	14.69.11.	Rendering an image in a JTable column
	14.69.12.	Setting the Activation Click Count for a Table Cell Editor in a JTable Component
	14.69.13.	Using DefaultTreeCellRenderer
	14.69.14.	Changing and Removing the Default Icons in a JTree Component
	14.69.15.	Use UIManager to change the default icon for JTree
	14.69.16.	Flush the internal cache of Row height