android - blank Recyclerview inside Fragment -

i using fragment , recyclerview together. have database , want query results coming database , display results inside activity.

however every time try run application , switch part , view results, don't seem anything. no results @ blank. don't know why it's not showing up.

this full code

sample class

public class sample extends fragment {     private view rootview;      public sample() {}      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);     }      @override     public view oncreateview(layoutinflater inflater, viewgroup container,                              bundle savedinstancestate) {         super.oncreateview(inflater, container, savedinstancestate);          rootview = inflater.inflate(sample, container, false);          recyclerview mrecyclerview = (recyclerview) rootview.findviewbyid(r.id.recyclerview_sample);         mrecyclerview.setlayoutmanager(new linearlayoutmanager(getactivity()));         mrecyclerview.sethasfixedsize(true);          databasehandler db= new databasehandler(getactivity());         list<samplemodel> list = db.getresults();          sampleadapter sampleadapter = new sampleadapter(list);         mrecyclerview.setadapter(sampleadapter);          return rootview;     } } 

adapter class

public class sampleadapter extends recyclerview.adapter <sampleadapter.viewholder> {      private list<samplemodel> list;     private context mcontext;      public sampleadapter (list<samplemodel> list) {         list = list;     }      @override     public sampleadapter.viewholder oncreateviewholder(viewgroup parent, int viewtype) {         view view = layoutinflater.from(mcontext).inflate(r.layout.sample_item, parent, false);         return new viewholder(view);     }      @override     public void onbindviewholder(sampleadapter.viewholder holder, int position) {         samplemodel sample = list.get(holder.getadapterposition());         holder.title.settext(sample.gettitle())     }      @override     public int getitemcount() {         return (list != null? list.size():0);     }      public class viewholder extends recyclerview.viewholder {          public textview title;          public viewholder(view itemview) {             super(itemview);             title = (textview) itemview.findviewbyid(r.id.title);         }     } } 

xml

sample.xml

    <?xml version="1.0" encoding="utf-8"?>     <android.support.design.widget.coordinatorlayout          xmlns:android="http://schemas.android.com/apk/res/android"         xmlns:tools="http://schemas.android.com/tools"         android:layout_width="match_parent"         android:layout_height="match_parent"         android:fitssystemwindows="true">          <include layout="@layout/sample_recyclerview" />      </android.support.design.widget.coordinatorlayout> 

sample_recyclerview.xml

<?xml version="1.0" encoding="utf-8"?> <relativelayout      xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     app:layout_behavior="@string/appbar_scrolling_view_behavior">      <android.support.v7.widget.recyclerview         android:id="@+id/recyclerview_sample"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:cliptopadding="false"/>  </relativelayout> 

sample_item.xml

<?xml version="1.0" encoding="utf-8"?> <android.support.v7.widget.cardview      xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:card_view="http://schemas.android.com/apk/res-auto"     android:id="@+id/cardview"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:layout_margintop="10dp"     android:layout_marginbottom="10dp"     android:layout_marginleft="16dp"     android:layout_marginright="16dp"     android:focusable="true"     android:clickable="true"     android:foreground="?android:attr/selectableitembackground"     card_view:cardbackgroundcolor="#808080">      <linearlayout         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:orientation="vertical"         android:padding="16dp">          <textview             android:id="@+id/title"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:textcolor="#ffffff" />      </linearlayout>  </android.support.v7.widget.cardview> 

in sampleadapter change

list = list; 

to

this.list = list;