List Model Controls - The Definitive Guide to Java Swing - page 496

Figure 13-20. Altering the JComboBox pop-up button
The source for the JComboBox example shown in Figure 13-20 follows in Listing 13-16.
Listing 13-16. Custom JComboBox Pop-up Button
import java.awt.*;
import javax.swing.*;
import javax.swing.plaf.*;
import javax.swing.plaf.basic.*;
public class PopupComboSample {
public static void main(String args[]) {
Runnable runner = new Runnable() {
public void run() {
String labels[] = {"Chardonnay", "Sauvignon", "Riesling", "Cabernet",
"Zinfandel", "Merlot", "Pinot Noir", "Sauvignon Blanc", "Syrah",
"Gewürztraminer"};
JFrame frame = new JFrame("Popup JComboBox");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComboBox comboBox = new JComboBox(labels);
comboBox.setMaximumRowCount(5);
comboBox.setUI((ComboBoxUI)MyComboBoxUI.createUI(comboBox));
frame.add(comboBox, BorderLayout.NORTH);
frame.setSize (300, 200);
frame.setVisible (true);
}
};
EventQueue.invokeLater(runner);
}
static class MyComboBoxUI extends BasicComboBoxUI {
public static ComponentUI createUI(JComponent c) {
return new MyComboBoxUI();
}