Java Swing, JComboBox dans la liste déroulante changer auditeur avant de cliquer

How to get notified for the mouse position change/pointing events 
from the JComboBox ?

• par implémente ItemListener, qui a tiré à deux reprises (SELECTED et DESELECTED)

ou

• d'y ajouter CustomRenderer

ou ...

trois Événements possibles pour JComboBox par exemple

import java.awt.Component;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.basic.BasicComboBoxRenderer;
public class ComboBoxHoverOver {
private JComboBox combo = new JComboBox();
public ComboBoxHoverOver() {
combo.setPrototypeDisplayValue("XXXXXXXXXXXXXXXXXXXXXX");
combo.setRenderer(new ComboToolTipRenderer(combo));
combo.addItemListener(new ItemListener() {
@Override
public void itemStateChanged(ItemEvent e) {
System.out.println(combo.getSelectedItem().toString());
}
});
combo.addItem("");
combo.addItem("Long text 4");
combo.addItem("Long text 3");
combo.addItem("Long text 2");
combo.addItem("Long text 1");
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(combo);
f.pack();
f.setVisible(true);
}
private class ComboToolTipRenderer extends BasicComboBoxRenderer {
private static final long serialVersionUID = 1L;
private JComboBox combo;
private JList comboList;
ComboToolTipRenderer(JComboBox combo) {
this.combo = combo;
}
@Override
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
if (comboList == null) {
comboList = list;
KeyAdapter listener = new KeyAdapter() {
@Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_DOWN || e.getKeyCode() == KeyEvent.VK_UP) {
int x = 5;
int y = comboList.indexToLocation(comboList.getSelectedIndex()).y;
System.out.println(comboList.getSelectedIndex());
}
}
};
combo.addKeyListener(listener);
combo.getEditor().getEditorComponent().addKeyListener(listener);
}
if (isSelected) {
System.out.println(value.toString());
}
return this;
}
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
ComboBoxHoverOver comboBoxHoverOver = new ComboBoxHoverOver();
}
});
}
}