android - Toolbar not visible in layout -

below layout, , when running toolbar not visible @ all, 2 tabs on tabview take entire screen. in preview in androidstudio see actionbar expect @ top. missing?

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/c">   <android.support.v7.widget.toolbar     android:id="@+id/my_toolbar2"     android:layout_height="wrap_content"     android:layout_width="fill_parent"      android:background="?attr/colorprimary"     android:layout_marginbottom="10dp"     app:theme="@style/themeoverlay.appcompat.dark.actionbar"      xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto" />   <relativelayout     xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:id="@+id/c2">   <android.support.design.widget.tablayout             android:layout_height="match_parent"             android:layout_width="match_parent"             android:id="@+id/tabs"             app:layout_scrollflags="scroll|enteralways"/>     </relativelayout>     <android.support.v4.view.viewpager xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     android:id="@+id/pager"     android:layout_width="match_parent"     android:layout_height="match_parent">      </android.support.v4.view.viewpager> 

here activity using layout:

public class tabletgallery extends appcompatactivity implements actionbar.tablistener {  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);    //to change body of overridden methods use file | settings | file templates.     setcontentview(r.layout.tablet_gallery);      // initilization      toolbar = (toolbar) findviewbyid(r.id.my_toolbar2);     setsupportactionbar(toolbar);     viewpager = (viewpager) findviewbyid(r.id.pager);     madapter = new tabspageradapter(getsupportfragmentmanager());     viewpager.setadapter(madapter);     tablayout tablayout = (tablayout) findviewbyid(r.id.tabs);     tablayout.setupwithviewpager(viewpager);     tablayout.addtab(tablayout.newtab().settext("tab 1"));     tablayout.addtab(tablayout.newtab().settext("tab 2")); 

user linearlayout root layout instead.

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/c">   <android.support.v7.widget.toolbar     android:id="@+id/my_toolbar2"     android:layout_height="wrap_content"     android:layout_width="fill_parent"      android:background="?attr/colorprimary"     android:layout_marginbottom="10dp"     app:theme="@style/themeoverlay.appcompat.dark.actionbar"      xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto" />   <android.support.design.widget.tablayout             android:layout_height="match_parent"             android:layout_width="match_parent"             android:id="@+id/tabs"             app:layout_scrollflags="scroll|enteralways"/>   <relativelayout     xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:id="@+id/c2">      <android.support.v4.view.viewpager xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     android:id="@+id/pager"     android:layout_width="match_parent"     android:layout_height="match_parent">      </android.support.v4.view.viewpager>      </relativelayout>       </linearlayout>