what is the use of enterAlwaysCollapsed

Question

I am studing Support Design liabrary.I cannot understand the use of enterAlwaysCollapsed.It seems it will influece on pull down,but I tried and find nothing changed. So,what is the use of enterAlwaysCollapsed,could you show me with a demo?

Answer 1

Let me answer it myself. First the activity theme is AppTheme.

    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>

And then Don't set fitsSystemWindows in xml.
Last use scroll flag scroll|enterAlways|enterAlwaysCollapsed.
The final effect is below