Try this .. this method works for me..!! hope it may help somebody..!!
<android.support.v7.widget.Toolbar
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/my_awesome_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
android:minHeight="?attr/actionBarSize"
app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" >
<TextView
android:id="@+id/toolbar_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:singleLine="true"
android:text="Toolbar Title"
android:textColor="@android:color/white"
android:textSize="18sp"
android:textStyle="bold" />
</android.support.v7.widget.Toolbar>
To display logo in toolbar try the below snippet. // Set drawable
toolbar.setLogo(ContextCompat.getDrawable(context, R.drawable.logo));
Let me know the result.