JFCCombo
public class ComboPanel extends JPanel {
String choices[] = {"Mercury", "Venus", "Earth", "Mars", "Saturn", "Jupiter", "Uranus","Neptune", "Pluto"};
JComboBox combo1 = new JComboBox();
JComboBox combo2 = new JComboBox();
for (int i=0;i<choices.length;i++) {
combo1.addItem (choices[i]); combo2.addItem (choices[i]);
combo2.setEditable(true); combo2.setSelectedItem("X");
combo2.setMaximumRowCount(4);
add(combo1); add(combo2);