java - Exception occurring in PagerAdapter -

this exception occurring , little of phone.

the exception:

java.lang.illegalstateexception: application's pageradapter changed adapter's contents without calling pageradapter#notifydatasetchanged! expected adapter item count: 0, found: 5 pager id: com.cutv.mobile.zshdclient:id/vp_content_newslist pager class: class android.support.v4.view.viewpager problematic adapter: class com.cutv.mobile.zs.hdclient.activity.newslistactivity$categoryadapter @ android.support.v4.view.viewpager.populate(viewpager.java:967) @ android.support.v4.view.viewpager.populate(viewpager.java:919) @ android.support.v4.view.viewpager.onmeasure(viewpager.java:1441) @ android.view.view.measure(view.java:16508) @ android.widget.relativelayout.measurechildhorizontal(relativelayout.java:719) @ android.widget.relativelayout.onmeasure(relativelayout.java:455) @ android.view.view.measure(view.java:16508) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5125) @ android.widget.framelayout.onmeasure(framelayout.java:310) @ android.view.view.measure(view.java:16508) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5125) @ android.widget.linearlayout.measurechildbeforelayout(linearlayout.java:1404) @ android.widget.linearlayout.measurevertical(linearlayout.java:695) @ android.widget.linearlayout.onmeasure(linearlayout.java:588) @ android.view.view.measure(view.java:16508) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5125) @ android.widget.framelayout.onmeasure(framelayout.java:310) @ com.android.internal.policy.impl.phonewindow$decorview.onmeasure(phonewindow.java:2291) @ android.view.view.measure(view.java:16508) @ android.view.viewrootimpl.performmeasure(viewrootimpl.java:1994) @ android.view.viewrootimpl.measurehierarchy(viewrootimpl.java:1191) @ android.view.viewrootimpl.performtraversals(viewrootimpl.java:1373) @ android.view.viewrootimpl.dotraversal(viewrootimpl.java:1078) @ android.view.viewrootimpl$traversalrunnable.run(viewrootimpl.java:5687) @ android.view.choreographer$callbackrecord.run(choreographer.java:761) @ android.view.choreographer.docallbacks(choreographer.java:574) @ android.view.choreographer.doframe(choreographer.java:544) @ android.view.choreographer$framedisplayeventreceiver.run(choreographer.java:747) @ android.os.handler.handlecallback(handler.java:733) @ android.os.handler.dispatchmessage(handler.java:95) @ android.os.looper.loop(looper.java:136) @ android.app.activitythread.main(activitythread.java:5014) @ java.lang.reflect.method.invokenative(native method) @ java.lang.reflect.method.invoke(method.java:515) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:805) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:621) @ dalvik.system.nativestart.main(native method) 

the code:

public class newslistactivity extends baseactivity implements     view.onclicklistener {  private intent msuperintent; private pageindicator mindicator; private viewpager mviewpager; private list<newsfragment> mlist; private categoryadapter madapter; private int mtitle; private progressbar mwait_pb; private categoryloadtask cdt; private string tag = "news";  @override protected int setlayout() {     return r.layout.activity_newslist; } @override protected void initbase() {     mwait_pb = (progressbar) findviewbyid(r.id.pb_wait_newslist);     mindicator = (pageindicator) findviewbyid(r.id.indicator_newslist);     mviewpager = (viewpager) findviewbyid(r.id.vp_content_newslist);     mlist = new arraylist<newsfragment>();     logutils.printdebug(tag, mlist.size() + "first");     cdt = new categoryloadtask();     cdt.execute();     logutils.printdebug(tag, mlist.size() + "four"); } @override public void onclick(view v) {     int id = v.getid();     if (id == r.id.btn_back_title) {         finishcurrentactivity();         cdt.cancel(true);         mlist.clear();         mlist=null;         mviewpager.clearfocus();         mviewpager=null;         mindicator =null;     } }  private class categoryadapter extends fragmentpageradapter {      public categoryadapter(fragmentmanager fm) {         super(fm);     }      @override     public int getcount() {         logutils.printdebug(tag, mlist.size() + "five");         return mlist.size();     }      @override     public charsequence getpagetitle(int position) {         return mlist.get(position).getinfo().title;     }      @override     public fragment getitem(int arg0) {         return mlist.get(arg0);     } } private class categoryloadtask extends asynctask<object, void, void> {      private string scontent;      @override     protected void onpreexecute() {         super.onpreexecute();         mwait_pb.setvisibility(view.visible);         madapter = new categoryadapter(getsupportfragmentmanager());         mviewpager.setadapter(madapter);         mindicator.setviewpager(mviewpager);     }      @override     protected void doinbackground(object... params) {         string categorytype = "news";         if (mtitle == r.string.life) {             categorytype = "life";         } else if (mtitle == r.string.goverment_affairs) {             categorytype = "gov";         }         scontent = wapi.get_content_from_remote_url(                 wapi.wapi_get_category_url + categorytype, 10000);         return null;     }      @override     protected void onpostexecute(void result) {         super.onpostexecute(result);         wapi.parse_category_content(scontent, mlist);         logutils.printdebug(tag, mlist.size() + "third");         madapter.notifydatasetchanged();         mindicator.notifydatasetchanged();         mwait_pb.setvisibility(view.gone);     } } @override protected void ondestroy() {     // todo auto-generated method stub     super.ondestroy();     cdt.cancel(true);     mlist.clear();     mlist=null;     mviewpager.clearfocus();     mviewpager=null;     mindicator =null;  }  }