Inflate a Viewstub that contains a Data Binding

Question

I have an abstract BaseActivity class with this layout:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:minHeight="?attr/actionBarSize" />

    <ViewStub
        android:id="@+id/activity_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

All activities in the app extends BaseActivity and overrides a method called getLayoutResID to provide its layout resource id which is inflated in the ViewStub. I do this to avoid having the Toolbar in each layout. The code in the base class that is used to inflate the layout is this:

private void setupLayout() {
    setContentView(R.layout.activity_base);

    ViewStub viewStub = (ViewStub) findViewById(R.id.activity_layout);
    viewStub.setLayoutResource(getLayoutResID());
    viewStub.inflate();
}

One of my activities use the new Data Binding system, below its layout:

<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable name="user" type="com.myapp.User" />
    </data>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@{user.name}" />
</layout>

Although the data binding works perfectly the problem is that the ToolBar is not visible. Any idea why the data binding engine removes/hides the toolbar in this activity?

Answer 1

ViewStubs requires special attention as they replace themselves when being inflated, rather than populating themselves. Read more on data-binding/guide#viewstubs

Another solution (to avoid ViewStub altogether) is to let your ConcreteActivities include a toolbar layout in their layout - instead of inflating a stub containing the toolbar. You'll also have less headache if you ever want to use custom a toolbar for an activity.