Using Mouse Scroll Button In JScrollPane

Question

Hi all.
Is it possible to use the mouse scroll button to scroll up or down in a JScrollPane, and if so, how?

Answer 1

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class test extends JFrame implements MouseWheelListener {
  BoxListener boxListener = new BoxListener();
  JComboBox comboBox;
  JScrollPane scrollPane;
  JLabel[] labels = new JLabel[3];
  int scrollUnitIncrement = 3;
  public test() {
    String[] comboItems = {
      "3", "5", "10", "15"
    comboBox = new JComboBox(comboItems);
    comboBox.addItemListener(boxListener);
    JPanel comboBoxPanel = new JPanel();
    comboBoxPanel.add(new JLabel("scroll unit increment"));
    comboBoxPanel.add(comboBox);
    JPanel panel = new JPanel();
    panel.setPreferredSize(new Dimension(350,300));
    panel.setBackground(Color.yellow);
    panel.setLayout(new GridBagLayout());
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.weightx = 1.0;
    gbc.fill = gbc.HORIZONTAL;
    gbc.gridwidth = gbc.REMAINDER;
    for(int j = 0; j < labels.length; j++) {
      labels[j] = new JLabel(" ", SwingConstants.CENTER);
      labels[j].setOpaque(true);
      labels[j].setBackground(Color.green);
      panel.add(labels[j], gbc);
    scrollPane = new JScrollPane(panel);
    scrollPane.addMouseWheelListener(this);
    getContentPane().add(comboBoxPanel, BorderLayout.NORTH);
    getContentPane().add(scrollPane, BorderLayout.CENTER);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(300,200);
    setLocation(300,200);
    setVisible(true);
  public void mouseWheelMoved(MouseWheelEvent e) {
    int scrollAmount;
    if(e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL)
      scrollAmount =
          e.getUnitsToScroll() * scrollUnitIncrement;
    else
      scrollAmount = e.getScrollAmount();
    labels[0].setText("Wheel rotation = " + e.getWheelRotation());
    labels[1].setText("Units to scroll = " + e.getUnitsToScroll());
    labels[2].setText("Scroll amount = " + scrollAmount);
  class BoxListener implements ItemListener {
    public void itemStateChanged(ItemEvent e) {
      String item = (String)e.getItem();
      scrollUnitIncrement = Integer.parseInt(item);
      JScrollBar verticalBar = scrollPane.getVerticalScrollBar();
      verticalBar.setUnitIncrement(scrollUnitIncrement);
  public static void main(String[] args) {
    new test();
}