The Preview pane displays default values for data binding expressions if provided.
For example :
android:layout_height="@{@dimen/main_layout_height, default=wrap_content}"
It will take wrap_content
while designing and will act as a wrap_content
in preview pane.
Another example is
android:text="@{user.name, default=`Preview Text`}"
It will display Preview Text
in preview pane but when you run it in device/emulator actual text binded to it will be displayed