android - How to force ListView to Invalidate -

i'm new android development, i've studied posts of site , have tried many different suggestions still can't solve problem.

i refer here implement drop-&-drop list view (i.e. user can long-press , drag list item reorder position. created custom listview, adapter , listactivity. here part of code of listactivity:

public class dragndroplistactivity extends listactivity {  /** called when activity first created. */ @override public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      setcontentview(r.layout.dragndroplistview);      arraylist<string> content = new arraylist<string>(mlistcontent.length);     (int i=0; < mlistcontent.length; i++) {         content.add(mlistcontent[i]);     }      setlistadapter(new dragndropadapter(this, new int[]{r.layout.dragitem}, new int[]{r.id.textview01}, content));//new dragndropadapter(this,content)     listview listview = getlistview();      if (listview instanceof dragndroplistview) {         ((dragndroplistview) listview).setdroplistener(mdroplistener);         ((dragndroplistview) listview).setremovelistener(mremovelistener);         ((dragndroplistview) listview).setdraglistener(mdraglistener);     }      listview.setonitemclicklistener(new onitemclicklistener() {         public void onitemclick(adapterview<?> parent, view view, int position, long id) {             log.i("", "onitemclick");         }     });  }  private droplistener mdroplistener =      new droplistener() {     public void ondrop(int from, int to) {         listadapter adapter = getlistadapter();         if (adapter instanceof dragndropadapter) {             ((dragndropadapter)adapter).ondrop(from, to);             getlistview().invalidateviews();         }     } }; 

my problem is: when dragged & dropped item new position, replaced properly. after that, when tried drag item again, previous item in position shown. problem recovered if put app background , put again.

inside "ondrop", list view invalidated. i've learned site invalidateviews() not run immediately, seems invalidateviews() never run until put app background ?! how can force list view redraw ?

more information: app ran in emulator problem happened in galaxy phone (4.1.2).

hope help, many !

check if works :

private droplistener mdroplistener =  new droplistener() { public void ondrop(int from, int to) {     listadapter adapter = getlistadapter();     if (adapter instanceof dragndropadapter) {        ((dragndropadapter)adapter).notifydatasetchanged();         ((dragndropadapter)adapter).ondrop(from, to);          getlistview().invalidate();      } } 

};