java - display a non-selectable default value for JComboBox -

i have jcombobox contains 3 items {"personel", "magasinier", "fournisseur"}.

i want jcombobox display value "choisir une option :", non-selectable value.

i tried code after initcomponents(); :

this.jcombobox1.setselecteditem("choisir une option :"); 

but doesn't work.

how can ?

you override selection code in jcombobox model, code such following sscce:

public class jcomboexample {    private static jframe frame = new jframe();   private static final string not_selectable_option = " - select option - ";   private static final string normal_option = "normal option";    public static void main(string[] args) throws exception {     jcombobox<string> combobox = new jcombobox<string>();      combobox.setmodel(new defaultcomboboxmodel<string>() {       private static final long serialversionuid = 1l;       boolean selectionallowed = true;        @override       public void setselecteditem(object anobject) {         if (!not_selectable_option.equals(anobject)) {           super.setselecteditem(anobject);         } else if (selectionallowed) {           // allow once           selectionallowed = false;           super.setselecteditem(anobject);         }       }     });      combobox.additem(not_selectable_option);     combobox.additem(normal_option);      frame.add(combobox);     frame.pack();     frame.setdefaultcloseoperation(jframe.dispose_on_close);      swingutilities.invokelater(new runnable() {       @override       public void run() {         frame.setvisible(true);       }     });   } } 

this display combo box intial selection of "- select option -". user selects option, not possible select original option again.