Xml file used for performing action on a nested layout when its id is not known

activity_nested_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:id="@+id/parent_container"
              xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <Button android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Hello"/>
    </LinearLayout>
</LinearLayout>