android - My ListView is not showing list of Items i entered? -

i have 2 separate tabs in android project. 1) user enters data 2) displays data list in tab has listview

data entry working well.. when change tab see list list not displayed.there no error or exception @ run time . providing code please me.

  1st fragment    import android.app.activity;  import android.app.fragment;  import android.content.intent;  import android.os.bundle;  import android.util.log;   import android.view.layoutinflater;  import android.view.menu;  import android.view.menuitem;  import android.view.view;  import android.view.viewgroup;   import android.widget.arrayadapter;   import android.widget.button;   import android.widget.edittext;   import android.widget.listview;    public class mainactivity extends fragment { adapterdata ad; button send; edittext text; listview names; arrayadapter<string> aa; listsactivity la; int count;  public mainactivity() {     // todo auto-generated constructor stub }   @override public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);    }   @override public view oncreateview(layoutinflater inflater, viewgroup container,         bundle savedinstancestate) {     // todo auto-generated method stub view rootview=inflater.inflate(r.layout.fragment1, container,false);     return rootview; }   @override public void onactivitycreated(bundle savedinstancestate) {     // todo auto-generated method stub     super.onactivitycreated(savedinstancestate);       activity temp=getactivity();      send=(button)temp.findviewbyid(r.id.button);     text=(edittext)temp.findviewbyid(r.id.edittext);     names=(listview)temp.findviewbyid(r.id.list);     ad=new adapterdata();     aa=new arrayadapter<string>(getactivity(), r.layout.how_to_display,ad.list);     names.setadapter(aa);       send.setonclicklistener(new view.onclicklistener() {          @override         public void onclick(view arg0) {              if(text.gettext()!=null)             {              ad.list.add(text.gettext().tostring());             log.i("mytag", ""+ad.list);               }          }     }); }   public void onclick(view view) {   log.i("mytag", "see list button clicked");      //intent ii=new intent(this,listsactivity.class);     //startactivity(ii); }    }    2nd fragment   import android.r.anim;  import android.app.fragment;  import android.app.listactivity;  import android.os.bundle;  import android.view.layoutinflater;  import android.view.view;  import android.view.viewgroup;  import android.view.viewgroup.layoutparams;  import android.widget.arrayadapter;  import android.widget.button;  import android.widget.listview;  import android.widget.textview;      public class listsactivity extends fragment{ adapterdata ad; listview names;  textview view; arrayadapter<string> aa;  public listsactivity() {     // todo auto-generated constructor stub }     @override public view oncreateview(layoutinflater inflater, viewgroup container,         bundle savedinstancestate) {     // todo auto-generated method stub     view rootview=inflater.inflate(r.layout.fragment_main, container,false);     return rootview; }   @override public void onactivitycreated(bundle savedinstancestate) {     // todo auto-generated method stub     super.onactivitycreated(savedinstancestate);       ad=new adapterdata();            names=(listview)getactivity().findviewbyid(r.id.list);    aa=new arrayadapter<string>(getactivity(),r.layout.how_to_display,r.id.empty, ad.list);                                 aa.notifydatasetchanged();      names.setadapter(aa);  }   }   main activity      import android.app.actionbar;     import android.app.actionbar.tab;     import android.app.activity;     import android.app.actionbar.tablistener;     import android.app.fragment;     import android.app.fragmenttransaction;     import android.os.bundle;     import android.util.log;       public class launchactivity extends activity implements tablistener {   fragment tab1,tab2; private string tag="mytag";    @override protected void oncreate(bundle savedinstancestate) {     // todo auto-generated method stub     super.oncreate(savedinstancestate);      setcontentview(r.layout.activity_main);     tab1=new mainactivity();     tab2=new listsactivity();      actionbar ab=getactionbar();     ab.setnavigationmode(actionbar.navigation_mode_tabs);     ab.addtab(ab.newtab().settext("enter items").settablistener(this));     ab.addtab(ab.newtab().settext("see list").settablistener(this)); }  @override public void ontabreselected(tab arg0, fragmenttransaction arg1) {     // todo auto-generated method stub  }  @override public void ontabselected(tab arg0, fragmenttransaction arg1) {     // todo auto-generated method stub      log.i(tag, "ontabselected");     if(arg0.gettext().equals("enter items"))     {   log.i(tag, "ontabselected");         getfragmentmanager().begintransaction().replace(r.id.linearlayout, tab1).commit();         log.i(tag, "ontabselected");      }      else     {log.i(tag, "ontabselected2");     //getfragmentmanager().begintransaction().remove(tab1);     getfragmentmanager().begintransaction().replace(r.id.linearlayout, tab2).commit();     log.i(tag, "ontabselected2");     }   }  @override public void ontabunselected(tab arg0, fragmenttransaction arg1) {     // todo auto-generated method stub  }         }