<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/drawerLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <!-- The main content view -->
    <FrameLayout
        android:id="@+id/content_frame"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <!-- The navigation drawer -->
    <ListView android:id="@+id/drawerList"
        android:layout_width="240dp"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:choiceMode="singleChoice"
        android:divider="@android:color/transparent"
        android:dividerHeight="0dp"
        android:background="#FFF"/>
</android.support.v4.widget.DrawerLayout>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/com_facebook_button_send_background_color"
android:weightSum="1">


<include
    android:id="@+id/app_bar"
    layout="@layout/app_bar"
    />
<include
    android:id="@+id/drawerLayout"
    layout="@layout/navigation_bar_layout"/>

<LinearLayout
    android:layout_width="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_height="match_parent"
    android:layout_below="@+id/app_bar"
    android:background="@color/com_facebook_button_send_background_color"
    >

    <Button
        android:layout_width="1in"
        android:layout_height="1.1in"
        android:id="@+id/docs_button"
        android:layout_weight="0.17"
        android:layout_gravity="center"
        android:background="@drawable/docs"
        />
           ....

public class HomeActivity extends AppCompatActivity  implements View.OnClickListener{

private static final String TAG = HomeActivity.class.getSimpleName();


private Toolbar toolbar;
private Button docsButton;
private Button musicButton;
private ListView drawerList;
private DrawerLayout drawerLayout;
private String [] drawerListValues;

@Override
protected void onCreate(Bundle savedInstanceSate) {

    Log.d(TAG ,"OnCreate() - Ini");

    super.onCreate(savedInstanceSate);

    setContentView(R.layout.home_layout);
    toolbar= (Toolbar) findViewById(R.id.app_bar);
    setSupportActionBar(toolbar);
    toolbar.setTitle(R.string.app_name);
    toolbar.setTitleTextColor(getResources().getColor(R.color.com_facebook_button_background_color_focused));
    drawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
    drawerList = (ListView) findViewById(R.id.drawerList);
    drawerListValues = getResources().getStringArray(R.array.drawerList);
    drawerList.setAdapter(new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,drawerListValues));