How do I get the selected nodes of a JTree?

By I Wayan Saryada in Swing 0 Comment

The following example show how to use the JTree.getSelectionPaths() method to get the selected node of a JTree component. This method returns an array of TreePath objects. In the case to get the last node in the path we can call the TreePath.getLastPathComponent().

In the code below when you pressed the button the listener gets the selection paths and print out the last path component of the selected nodes.

package org.kodejava.swing;

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

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

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new JTreeGetSelectedNode().setVisible(true));
    }

    private void initializeUI() {
        setSize(500, 500);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        DefaultMutableTreeNode root = new DefaultMutableTreeNode("Countries");
        DefaultMutableTreeNode asia = new DefaultMutableTreeNode("Asia");
        String[] countries = new String[]{"India", "Singapore", "Indonesia", "Vietnam"};
        for (String country : countries) {
            DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
            asia.add(node);
        }

        DefaultMutableTreeNode northAmerica = new DefaultMutableTreeNode("North America");
        countries = new String[]{"United States", "Canada"};
        for (String country : countries) {
            DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
            northAmerica.add(node);
        }

        DefaultMutableTreeNode southAmerica = new DefaultMutableTreeNode("South America");
        countries = new String[]{"Brazil", "Argetina", "Uruguay"};
        for (String country : countries) {
            DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
            southAmerica.add(node);
        }

        DefaultMutableTreeNode europe = new DefaultMutableTreeNode("Europe");
        countries = new String[]{"United Kingdom", "Germany", "Spain", "France", "Italy"};
        for (String country : countries) {
            DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
            europe.add(node);
        }

        root.add(asia);
        root.add(northAmerica);
        root.add(southAmerica);
        root.add(europe);

        final JTree tree = new JTree(root);
        JScrollPane pane = new JScrollPane(tree);
        pane.setPreferredSize(new Dimension(500, 500));

        JButton button = new JButton("Get Selected");
        button.addActionListener(e -> {
            TreePath[] paths = tree.getSelectionPaths();
            for (TreePath path : paths != null ? paths : new TreePath[0]) {
                System.out.println("You've selected: " + path.getLastPathComponent());
            }
        });

        getContentPane().setLayout(new BorderLayout());
        getContentPane().add(pane, BorderLayout.CENTER);
        getContentPane().add(button, BorderLayout.SOUTH);
    }
}

How do I change JTree default icons?

By I Wayan Saryada in Swing 0 Comment

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.swing;

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

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

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

    private void intializeUI() {
        setSize(500, 500);
        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(Objects.requireNonNull(
                this.getClass().getResource("/images/lightbulb_off.png")));
        Icon openIcon = new ImageIcon(Objects.requireNonNull(
                this.getClass().getResource("/images/lightbulb.png")));
        Icon leafIcon = new ImageIcon(Objects.requireNonNull(
                this.getClass().getResource("/images/lightning.png")));
        renderer.setClosedIcon(closedIcon);
        renderer.setOpenIcon(openIcon);
        renderer.setLeafIcon(leafIcon);

        JScrollPane pane = new JScrollPane(tree);
        pane.setPreferredSize(new Dimension(500, 500));

        getContentPane().add(tree);
    }
}

How do I remove JTree default icons?

By I Wayan Saryada in Swing 0 Comment

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.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();
    }

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

    private void initializeUI() {
        setSize(500, 500);
        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);
    }
}
Remove JTree Default Icon

Remove JTree Default Icon

How do I add selection listener to JTree?

By I Wayan Saryada in Swing 0 Comment

This example shows you how to use the TreeSelectionListener to add a tree selection listener to the JTree component. In the listener method below you can see how to get the selected path and print out the selected path to the console.

package org.kodejava.swing;

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

public class JTreeSelectionListenerDemo extends JFrame {

    public JTreeSelectionListenerDemo() throws HeadlessException {
        initializeUI();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(
                () -> new JTreeSelectionListenerDemo().setVisible(true));
    }

    private void initializeUI() {
        setSize(500, 500);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        DefaultMutableTreeNode root = new DefaultMutableTreeNode("Root");
        DefaultMutableTreeNode chapterOne = new DefaultMutableTreeNode("Chapter One");
        DefaultMutableTreeNode one = new DefaultMutableTreeNode("1.1");
        DefaultMutableTreeNode two = new DefaultMutableTreeNode("1.2");
        DefaultMutableTreeNode three = new DefaultMutableTreeNode("1.3");

        root.add(chapterOne);
        chapterOne.add(one);
        chapterOne.add(two);
        chapterOne.add(three);

        JTree tree = new JTree(root);
        tree.addTreeSelectionListener(e -> {
            TreePath path = e.getPath();
            int pathCount = path.getPathCount();

            for (int i = 0; i < pathCount; i++) {
                System.out.print(path.getPathComponent(i).toString());
                if (i + 1 != pathCount) {
                    System.out.print(" | ");
                }
            }
            System.out.println();
        });

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

        getContentPane().add(pane);
    }
}

How do I change color of selected node in JTree?

By I Wayan Saryada in Swing 0 Comment

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.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();
    }

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

    private void initializeUI() {
        setSize(500, 500);
        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.red);

        JScrollPane pane = new JScrollPane(tree);
        pane.setPreferredSize(new Dimension(250, 350));

        getContentPane().add(pane);
    }
}
JTree Node Color Demo

JTree Node Color Demo