import java.awt.BorderLayout;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.WindowConstants;

public class test extends javax.swing.JFrame  {
    private JComboBox jComboBox1 = new JComboBox();;
    
    public test() {
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        jComboBox1.setEditable(true);
                        
        jComboBox1.addFocusListener(new FocusListener(){ 
            public void focusGained(FocusEvent evt){
                System.out.println("Focus on JComboBox gained");
            }
            public void focusLost(FocusEvent evt){
                System.out.println("Focs on JCombBox lost");
            }
        });
         
        getContentPane().add(jComboBox1, BorderLayout.CENTER);
        pack();
    }
        
    public static void main(String args[]) {
        final JFrame frame = new test();
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                frame.setVisible(true);                
            }
        });        
    }
}