Android / Java: Show GUI on "off-screen" (Always-On Display...)
<p>I saw new Android devices coming out, that show things (clock etc.) once the display "turns off". That feature is called an Always-On Display, and since my Samsung Galaxy S6 edge already features an AMOLED screen, and a night-clock, I believe there is a way, to make it show something, when the display is "turned off". Is there a way using Java on Android, to display something, once display is meant to turn off? (Like just a normal GUI, I could do the rest then.)
Like, to tell your app, to show something, when the screen turns off, that is still visible somehow? (without root permissions)</p>

<p>That would be useful, thanks in advance.</p>

<p>UPDATE:
I found some apps on the Google Play Store, which seem do to, what I want (not that specialized though):
<a href="https://play.google.com/store/apps/details?id=com.thsoft.glance&amp;hl=de" rel="nofollow">https://play.google.com/store/apps/details?id=com.thsoft.glance&amp;hl=de</a>
<a href="https://play.google.com/store/apps/details?id=com.orthur.always_on_display&amp;hl=de" rel="nofollow">https://play.google.com/store/apps/details?id=com.orthur.always_on_display&amp;hl=de</a></p>

<p>So it is definetely possible, I just need to know, how.</p>