About JComboBox's event

Question

below is resource
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class ComboBoxTest extends JFrame{
    private JLabel sqlLabel = new JLabel("SQL:");
    private JComboBox sqlComboBox = new JComboBox();
    public ComboBoxTest() {
        sqlComboBox.setEditable(true);
        sqlComboBox.addItem("");
        sqlComboBox.setBackground(Color.WHITE);
        sqlComboBox.setPreferredSize(new Dimension(500,25));
        sqlComboBox.addItemListener(new ItemListener() {
            public void itemStateChanged(ItemEvent event) {
                if (event.getStateChange() == ItemEvent.SELECTED){
                    if(sqlComboBox.getSelectedIndex()==-1){
                        String currentSQL=(String)event.getItem();
                        System.out.println("currentSQL : "+currentSQL);
                        sqlComboBox.addItem(currentSQL);
        Container cp=getContentPane();
        cp.setLayout(new FlowLayout());
        cp.add(sqlLabel);
        cp.add(sqlComboBox);
        pack();
        setVisible(true);
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent evt) {
                System.exit(0);
    public static void main(String[] args){
        new ComboBoxTest();
}my intent is that let user write sql in JComboBox,this program will send sql when user click enter,and JComboBox will use addItem() to add the sql to JComboBox,
problem is below:
when I clicked enter one more time,why just can arosed only itemStateChanged event,I hope this program would arose itemStateChanged event when user clicked enter everytime
another:
when user choosed the sql that has been used addItem() to add JComboBox;
why then clicked enter would not arose any itemStateChanged event

Answer 1

1) I've answered several of your previous postings. Not once have you bothered to follow up the posting to confirm the suggestion worked, or didn't work. A simple Thank You goes a long way.
2) Several times I've also suggested that Swing related questions should be posted on the Swing forum. (This is where the Swing experts hang out).
3) I don't understand your question, so I can't help anyway.