android - (Solved) java.lang.NullPointerException: Attempt to invoke virtual method ... on a null object reference -

i have class called resultactivity display list of place'info. activity request server , receive json object. activity doesn't work , found error

java.lang.runtimeexception: unable start activity componentinfo{com.example.shameal/com.example.shameal.resultactivity}: java.lang.nullpointerexception: attempt invoke virtual method 'com.android.volley.toolbox.imageloader com.example.shameal.controller.appcontroller.getimageloader()' on null object reference 

resultactivity

public class resultactivity extends listactivity{ private listview listview; private feedlistadapter listadapter; private list<feeditem> feeditems;  @override protected void oncreate(bundle savedinstancestate) {     // todo auto-generated method stub     super.oncreate(savedinstancestate);     ...      listview = (listview) findviewbyid(r.id.list);     feeditems = new arraylist<feeditem>();     listadapter = new feedlistadapter(this, feeditems);     listview.setadapter(listadapter);      ... } 

feedlistadapter

public class feedlistadapter extends baseadapter {   private activity activity; private layoutinflater inflater; private list<feeditem> feeditems; imageloader imageloader = appcontroller.getinstance().getimageloader();  public feedlistadapter(activity activity, list<feeditem> feeditems) {     this.activity = activity;     this.feeditems = feeditems; }  @override public int getcount() {     return feeditems.size(); }  @override public object getitem(int location) {     return feeditems.get(location); }  @override public long getitemid(int position) {     return position; }  @override public view getview(int position, view convertview, viewgroup parent) {      if (inflater == null)         inflater = (layoutinflater) activity                 .getsystemservice(context.layout_inflater_service);     if (convertview == null)         convertview = inflater.inflate(r.layout.feed_item, null);      if (imageloader == null)         imageloader = appcontroller.getinstance().getimageloader();      textview name = (textview) convertview.findviewbyid(r.id.name);     textview address = (textview) convertview             .findviewbyid(r.id.address);     textview description = (textview) convertview             .findviewbyid(r.id.description);     textview rate = (textview) convertview.findviewbyid(r.id.rate);     networkimageview image = (networkimageview) convertview             .findviewbyid(r.id.image);     feedimageview feedimageview = (feedimageview) convertview             .findviewbyid(r.id.feedimage1);      feeditem item = feeditems.get(position);      name.settext(item.getname());      // converting timestamp x ago format     address.settext(item.getaddress());      // chcek empty status message     if (!textutils.isempty(item.getdescription())) {         description.settext(item.getdescription());         description.setvisibility(view.visible);     } else {         // status empty, remove view         description.setvisibility(view.gone);     }      rate.settext(item.getrate());     image.setimageurl(item.getimage(), imageloader);      // feed image     if (item.getmenu() != null || item.getmenu() != "0") {         feedimageview.setimageurl(item.getmenu(), imageloader);         feedimageview.setvisibility(view.visible);         feedimageview                 .setresponseobserver(new feedimageview.responseobserver() {                     @override                     public void onerror() {                     }                      @override                     public void onsuccess() {                     }                 });     } else {         feedimageview.setvisibility(view.gone);     }      return convertview; } 

}

i think error in line: listadapter = new feedlistadapter(this, feeditems); can not found solution fix it.

thanks help!

edited: followed tutorial: http://www.androidhive.info/2014/06/android-facebook-like-custom-listview-feed-using-volley/. use code of tutorial app doesn't work.

add 1 line manifest

<application     android:name=".appcontroller" //this 1     android:allowbackup="true"     android:icon="@drawable/ic_launcher"     android:label="@string/app_name"     android:theme="@style/apptheme">