listview - opening application detail setting intent from list-view showing list of installed applications [Android] -

i developing application manager app android in installed applications displayed in listview using package-manager class. wanted open action_application_details_settings intent of selected application using onitemclicklistener() on listview when position adapterview doesn't open settings of selected application. have searched lot issue on stackoverflow doesn't found right solution. code following:

public class activity_appmanager extends appcompatactivity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.layout_app_manager);         toolbar toolbar = (toolbar) findviewbyid(r.id.toolbar);         setsupportactionbar(toolbar);         getsupportactionbar().setdisplayhomeasupenabled(true);          listview userinstalledapps = (listview)findviewbyid(r.id.installed_app_list);          list<applist> installedapps = getinstalledapps();         appadapter installedappadapter = new appadapter(activity_appmanager.this, installedapps);         userinstalledapps.setadapter(installedappadapter);          list<applist> res = new arraylist<applist>();         final list<packageinfo> packs = getpackagemanager().getinstalledpackages(0);          userinstalledapps.setonitemclicklistener(new adapterview.onitemclicklistener() {             @override             public void onitemclick(adapterview<?> adapterview, view view, int position, long l) {                  packageinfo p = packs.get(position);                 string packagename = p.applicationinfo.packagename;                 // packageinfo packageinfo = (packageinfo) adapterview.getitematposition(position);                 toast.maketext(activity_appmanager.this, "" + packagename, toast.length_short).show();                 intent intent = new intent(android.provider.settings.action_application_details_settings);                 intent.setflags(intent.flag_activity_new_task);                 intent.setdata(uri.parse("package:" + packagename));                 startactivity(intent);             }         });      }      private list<applist> getinstalledapps() {         list<applist> res = new arraylist<applist>();         list<packageinfo> packs = getpackagemanager().getinstalledpackages(0);         (int = 0; < packs.size(); i++) {             packageinfo p = packs.get(i);             if ((issystempackage(p) == false)) {                 string appname = p.applicationinfo.loadlabel(getpackagemanager()).tostring();                 drawable icon = p.applicationinfo.loadicon(getpackagemanager());                 res.add(new applist(appname, icon));             }         }         return res;     }      private boolean issystempackage(packageinfo pkginfo) {         return ((pkginfo.applicationinfo.flags & applicationinfo.flag_system) != 0) ? true : false;     }  }