Synchronize 2 Jcombobox - double the action?

Question

Hi all,
I have asked how to synchronize 2 Jcombobox before, and the solution works, which is:
JComboBox myCB1 = new JComboBox(...);
JComboBox myCB2 = new JComboBox(...);
myCB1.addActionListener(
   new ActionListener() {
      public void actionPerformed(ActionEvent e) {
         int index = myCB1.getSelectedIndex();
         myCB2.setSelectedIndex(index);
myCB2.addActionListener(
   new ActionListener() {
      public void actionPerformed(ActionEvent e) {
         int index = myCB2.getSelectedIndex();
         myCB1.setSelectedIndex(index);
); However, now I ran into a problem which the action perform by one of the ComboBox is done twice because the 2 combo are calling each other.
In one case which I try to print out the items in a final array (initiate by selecting an itrem in the comboBox), it runs into and infinite loop.
I've tried flipping an gobal boolean, which the comboBox only perform the action when the boolean is true, and after each action I flip the boolean. But this sort of disable the synchronization of the comboBox.
Could anyone please help me here?
Sam

Answer 1

If they are already in synch, then there is nothing else to do...
JComboBox myCB1 = new JComboBox(...);
JComboBox myCB2 = new JComboBox(...);
myCB1.addActionListener(
   new ActionListener() {
      public void actionPerformed(ActionEvent e) {
         int index = myCB1.getSelectedIndex();
         if(myCB2.getSelectedIndex() != index) {
           myCB2.setSelectedIndex(index);
myCB2.addActionListener(
   new ActionListener() {
      public void actionPerformed(ActionEvent e) {
         int index = myCB2.getSelectedIndex();
         if(myCB1.getSelectedIndex() != index) {
           myCB1.setSelectedIndex(index);
);