import java.awt.*;
import java.awt.event.*;
import javax.swing.*; 
public class Test extends JApplet {
private JComboBox comboBox = new JComboBox();

public void init() {
Container contentPane = getContentPane();

comboBox.addItem("Top");
comboBox.addItem("Center");
comboBox.addItem("Bottom");

contentPane.setLayout(new FlowLayout());
contentPane.add(comboBox);

comboBox.addItemListener(new ItemListener() { 
public void itemStateChanged(ItemEvent event) {
int state = event.getStateChange();
String item = (String)event.getItem(), s;

if(event.getStateChange() == ItemEvent.SELECTED)
s = " selected";
else
s = " deselected";

JOptionPane.showMessageDialog(
comboBox, // parent component
item + s, // message
"JComboBox Selection", // title
JOptionPane.INFORMATION_MESSAGE); // type
}
});
}
}