android - Fragment findviewbyid not working correctly -

i have tablet layout , phone layout , need tablet detect whether view exists determine whether execute tablet code or phone code.

this code in activity fragment attached returns true, same code in fragment returns false.

mtwopane = view.findviewbyid(r.id.detail_container) != null; 

what happening causing this? i've tried several things such mtwopane = getactivity().getrootview().findviewbyid(r.id.detail_container) != null; no luck.

my activity_main.xml phone:

<fragment 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:id="@+id/mainfragment"     android:name="com.project.mainfragment"     tools:context="com.project.mainfragment"/> 

my activity_main tablet:

<linearlayout 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:baselinealigned="false"     android:divider="?android:attr/dividerhorizontal"     android:orientation="horizontal"     tools:context="com.project.mainactivity">      <fragment         android:layout_width="0dp"         android:layout_weight="1"         android:layout_height="match_parent"         android:id="@+id/mainfragment"         android:name="com.project.mainfragment" />      <framelayout         android:layout_width="0dp"         android:layout_weight="1"         android:layout_height="match_parent"         android:id="@+id/detail_container"/> </linearlayout> 

my mainactivity's oncreate:

@override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);     if (findviewbyid(r.id.detail_container) != null) {         mtwopane = true;         if (savedinstancestate == null) {             getsupportfragmentmanager()                     .begintransaction()                     .replace(r.id.detail_container, new detailfragment(), detailfragment_tag)                     .commit();         }     } else {         mtwopane = false;     }     log.e(tag, boolean.tostring(mtwopane)); } 

my fragment's oncreateview:

@override public view oncreateview(layoutinflater inflater, viewgroup container,                          bundle savedinstancestate) {     view view = inflater.inflate(r.layout.fragment_main, container, false);     mtwopane = view.findviewbyid(r.id.detail_container) != null;     log.e(tag, boolean.tostring(mtwopane));     return view; }