How do I change JTree default icons?

The program below demonstrate how to change the default icons of a JTree component. We can change tree icons of the component which are the closed icon, the open icon and the leaf icon.

package org.kodejava.example.swing;

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

public class JTreeChangeIcon extends JFrame {
    public JTreeChangeIcon() throws HeadlessException {
        intializeUI();
    }

    private void intializeUI() {
        setSize(200, 400);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        DefaultMutableTreeNode root = new DefaultMutableTreeNode("Address Book");
        DefaultMutableTreeNode a = new DefaultMutableTreeNode("A");
        DefaultMutableTreeNode b = new DefaultMutableTreeNode("B");
        DefaultMutableTreeNode c = new DefaultMutableTreeNode("C");

        DefaultMutableTreeNode aContact = new DefaultMutableTreeNode("Alice");
        DefaultMutableTreeNode bContact = new DefaultMutableTreeNode("Bob");
        DefaultMutableTreeNode cContact = new DefaultMutableTreeNode("Carol");

        root.add(a);
        root.add(b);
        root.add(c);

        a.add(aContact);
        b.add(bContact);
        c.add(cContact);

        JTree tree = new JTree(root);

        // Change the default JTree icons
        DefaultTreeCellRenderer renderer = (DefaultTreeCellRenderer) tree.getCellRenderer();
        Icon closedIcon = new ImageIcon("closed.png");
        Icon openIcon = new ImageIcon("open.png");
        Icon leafIcon = new ImageIcon("leaf.png");
        renderer.setClosedIcon(closedIcon);
        renderer.setOpenIcon(openIcon);
        renderer.setLeafIcon(leafIcon);

        JScrollPane pane = new JScrollPane(tree);
        pane.setPreferredSize(new Dimension(200, 400));

        getContentPane().add(tree);        
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new JTreeChangeIcon().setVisible(true);
            }
        });
    }
}

How do I remove JTree default icons?

You can remove JTree default icons by modifying the tree cell renderer object. To get the cell renderer call the JTree.getCellRenderer() which will return a DefaultTreeCellRenderer object. Then you can remove the icon by setting a null value to the setLeafIcon(), setClosedIcon() and setOpenIcon().

package org.kodejava.example.swing;

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

public class JTreeRemoveIcon extends JFrame {
    public JTreeRemoveIcon() throws HeadlessException {
        initializeUI();
    }

    private void initializeUI() {
        setSize(200, 400);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        DefaultMutableTreeNode root = new DefaultMutableTreeNode("Address Book");
        DefaultMutableTreeNode a = new DefaultMutableTreeNode("A");
        DefaultMutableTreeNode b = new DefaultMutableTreeNode("B");
        DefaultMutableTreeNode c = new DefaultMutableTreeNode("C");

        DefaultMutableTreeNode aContact = new DefaultMutableTreeNode("Alice");
        DefaultMutableTreeNode bContact = new DefaultMutableTreeNode("Bob");
        DefaultMutableTreeNode cContact = new DefaultMutableTreeNode("Carol");

        root.add(a);
        root.add(b);
        root.add(c);

        a.add(aContact);
        b.add(bContact);
        c.add(cContact);

        JTree tree = new JTree(root);

        // Remove default JTree icons
        DefaultTreeCellRenderer renderer = (DefaultTreeCellRenderer) tree.getCellRenderer();
        renderer.setLeafIcon(null);
        renderer.setClosedIcon(null);
        renderer.setOpenIcon(null);

        JScrollPane pane = new JScrollPane(tree);
        pane.setPreferredSize(new Dimension(200, 400));

        getContentPane().add(tree);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new JTreeRemoveIcon().setVisible(true);
            }
        });
    }
}

How do I change color of selected node in JTree?

This example show you how to change the color of the selected node of the JTree component. It shows you how to set the node background color, the font color and the selected node border color.

To do this you need to obtain the DefaultTreeCellRenderer object from the JTree instance and modified the selection color of the node.

package org.kodejava.example.swing;

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

public class JTreeTextSelectionColorDemo extends JFrame {
    public JTreeTextSelectionColorDemo() throws HeadlessException {
        initializeUI();
    }

    private void initializeUI() {
        setSize(150, 300);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        DefaultMutableTreeNode root = new DefaultMutableTreeNode("Department");
        DefaultMutableTreeNode book = new DefaultMutableTreeNode("Books");
        DefaultMutableTreeNode fiction = new DefaultMutableTreeNode("Fictions");
        DefaultMutableTreeNode science = new DefaultMutableTreeNode("Sciences");
        DefaultMutableTreeNode text = new DefaultMutableTreeNode("Text Books");
        DefaultMutableTreeNode children = new DefaultMutableTreeNode("Children");

        root.add(book);
        book.add(fiction);
        book.add(science);
        book.add(text);
        book.add(children);

        JTree tree = new JTree(root);

        // Get the DefaultTreeCellRenderer instance of the JTree
        // component. Then we customize the color of the selection
        // node using blue background, white font color and black
        // border.
        DefaultTreeCellRenderer renderer = (DefaultTreeCellRenderer) tree.getCellRenderer();
        renderer.setTextSelectionColor(Color.white);
        renderer.setBackgroundSelectionColor(Color.blue);
        renderer.setBorderSelectionColor(Color.black);

        JScrollPane pane = new JScrollPane(tree);
        pane.setPreferredSize(new Dimension(150, 300));

        getContentPane().add(pane);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new JTreeTextSelectionColorDemo().setVisible(true);
            }
        });
    }
}