plugins - How to update a drop down list of a pull down button in the Eclipse toolbar? -

i have added drop down list dynamically pull down button in eclipse toolbar, following instructions: programmatically add options pulldown button in eclipse

now, need update drop down list. idea remove old list , add new list pull down button. tried methods: removecontributionfactory(abstractcontributionfactory factory) , dispose() of imenuservice, none of them works. give me tips of how achieve goal?

here code used:

(1) in class a, invoke method add drop down list pull down button (command)

class {  public static contextswitchcontributionfactory contextfactory =    new contextswitchcontributionfactory("menu:"+"switchcontext", null);  public static imenuservice menuservice =   (imenuservice)platformui.getworkbench().getservice(imenuservice.class);   ...  method () {  ...  contextswitchcontributionfactory.updatecontextmenu(menuservice, contextfactory, "switchcontext");  ...  } 

(2) definition of contextswitchcontributionfactory:

public class contextswitchcontributionfactory extends abstractcontributionfactory {   private contextdata contextdata = new contextdata();   private contextscollector contextlist;  }  static public void updatecontextmenu (imenuservice service, final abstractcontributionfactory       factory, final string menuid) {    service.dispose();   service.addcontributionfactory(factory);  }    public contextswitchcontributionfactory(string location, string namespace) {   super(location, namespace);   // read file , update data creating drop down list      contextdata.readcontextsfile();   contextlist = contextdata.getcontextscollector(); }   @override public void createcontributionitems(iservicelocator servicelocator,   icontributionroot additions) {  set<icontext> cxtset = contextlist.getcontextlist(); iterator<icontext> iterator = cxtset.iterator();  while (iterator.hasnext()) {    icontext context = iterator.next();   commandcontributionitemparameter menuitem = new commandcontributionitemparameter(       servicelocator, null,        "coms.sample.command.context",       commandcontributionitem.style_push);        menuitem.label = context.getname();   menuitem.visibleenabled = true;    if (context.isselected()) {      imagedescriptor image = mechanicplugin.getimagedescriptor("icons/ticking_icon.png");      menuitem.icon = image;   }    additions.addcontributionitem(new commandcontributionitem(menuitem), null);   }   } } 

(3) in method c of class c, want update drop down list:

class c { ... method c { ...   // a.menuservice.dispose(); (doesn't work)   // remove old 1   a.menuservice.removecontributionfactory(a.contextfactory);   // create new 1    a.contextfactory =      new contextswitchcontributionfactory("menu:"+"switchcontext", null);   // after executing statement, old drop down list still there, , new 1             added after old list.   a.menuservice.addcontributionfactory(a.contextfactory);   contextswitchcontributionfactory.updatecontextmenu(menuservice, contextfactory,      "switchcontext"); .. 

i think have found answer, method used, nature, drop down list cannot updated. add drop down list can refreshed, dynamic elements should used: static , dynamic pulldown menus