import java.awt.BorderLayout;

import java.awt.Component;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.util.Vector;

import javax.swing.JComboBox;

import javax.swing.JFrame;

import javax.swing.JList;

import javax.swing.plaf.basic.BasicComboBoxRenderer;

public class Main extends JFrame implements ActionListener {

public Main() {

Vector model = new Vector();

model.addElement(new Item(1, "A"));

model.addElement(new Item(2, "B"));

model.addElement(new Item(3, "C"));

model.addElement(new Item(4, "D"));

JComboBox comboBox = new JComboBox(model);

comboBox.addActionListener(this);

comboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);

getContentPane().add(comboBox, BorderLayout.NORTH);

comboBox = new JComboBox(model);

comboBox.setRenderer(new ItemRenderer());

comboBox.addActionListener(this);

getContentPane().add(comboBox, BorderLayout.SOUTH);

}

public void actionPerformed(ActionEvent e) {

JComboBox comboBox = (JComboBox) e.getSource();

Item item = (Item) comboBox.getSelectedItem();

System.out.println(item.getId() + " : " + item.getDescription());

}

public static void main(String[] args) {

JFrame frame = new Main();

frame.setDefaultCloseOperation(EXIT_ON_CLOSE);

frame.pack();

frame.setVisible(true);

}

}

class ItemRenderer extends BasicComboBoxRenderer {

public Component getListCellRendererComponent(JList list, Object value,

int index, boolean isSelected, boolean cellHasFocus) {

super.getListCellRendererComponent(list, value, index, isSelected,

cellHasFocus);

if (value != null) {

Item item = (Item) value;

setText(item.getDescription().toUpperCase());

}

if (index == -1) {

Item item = (Item) value;

setText("" + item.getId());

}

return this;

}

}

class Item {

private int id;

private String description;

public Item(int id, String description) {

this.id = id;

this.description = description;

}

public int getId() {

return id;

}

public String getDescription() {

return description;

}

public String toString() {

return description;

}

}