import javax.swing.JComboBox; import javax.swing.event.PopupMenuEvent; import javax.swing.event.PopupMenuListener; public class Main { public static void main(String[] argv) throws Exception { String[] items = { "item1", "item2" }; JComboBox cb = new JComboBox(items); cb.setEditable(true); MyPopupMenuListener actionListener = new MyPopupMenuListener(); cb.addPopupMenuListener(actionListener); } } class MyPopupMenuListener implements PopupMenuListener { public void popupMenuWillBecomeVisible(PopupMenuEvent evt) { JComboBox cb = (JComboBox) evt.getSource(); } public void popupMenuWillBecomeInvisible(PopupMenuEvent evt) { JComboBox cb = (JComboBox) evt.getSource(); } public void popupMenuCanceled(PopupMenuEvent evt) { JComboBox cb = (JComboBox) evt.getSource(); } }