Can you use a physical buttons to control an android application interface with and without?

Android interface control mobile development

I imagine: Can be put your own android applications running on a single instrument, just run the program is the interface, but I press a physical button on the instrument so that the interface disappears after (of course, not like on a mobile phone or tablet The back button does) but the program (a daemon) has been running, that at this time the entire interface on the instrument are not, when I need to make some settings, click the application's interface has emerged after the physical buttons .
My premise is this: I started a boot program, and the entire instrument may only be an interface (ie, the interface of the application); rather than as the disappearance of the interface of the application, android system interface is still like a cell phone.<-! Main posts under Banner (D4) -><-! Posts under the main text (D5) ->
Reply:
Only one interface, buttons have disappeared after that you can only put out the screen button, and let CPU sleep extinguished screen, click the screen lights up.
Your application can be made launcher.
Reply:
Ah, I see what you mean, is not a boot into the android system interface but directly open the application displays the application's interface, I was a little impression, seemingly before my teacher showed me their is such a project. After the physical power button is pressed knowledge so that the screen is actually the interface is still somewhat similar to what we play music with kougou, press the power button to put out the screen, bright screen display or kougou music player interface is pressed again. Thank tantahe it!
Reply:
Laughed at it, kugou are wrong, sorry!