Catch back button press event when screen locked

Question

I am trying to write a small app that will catch the KeyEvent of the back button been pressed, when the screen is locked.
I saw that you can easily override onKeyDown or onBackPressed in order to catch this event, but this will work only if the activity is running.
As I understand on some of the android phones, if not on all of them, the OS doesn't listen to the back and menu buttons while the screen is locked.

EDIT
I have read couple of posts about capturing the event of the user pressing the volume buttons, and all says their isn't a way to do so when the screen is off.
Is their a reason to belive the case is change regarding the back button?

So first you need to find the screen locked or not inside a service — Sree, Apr 23 '15 at 08:27
Most phones these days have no active back button when the screen is off. They have on screen navigation (nav bar) — Rolf ツ, Apr 23 '15 at 09:09

score 3 · Accepted Answer · answered Apr 23 '15 at 08:39

1)Register with BroadCast Receiver for Intent.ACTION_SCREEN_OFF and Intent.ACTION_SCREEN_ON

2) Check if Screen is locked using Keyguard Manager like :

KeyguardManager kManager = (KeyguardManager) getSystemService(Context.KEYGUARD_SERVICE);
boolean isLocked = kManager.inKeyguardRestrictedInputMode();

or without using BroadCast Receiver, you can check like :

KeyguardManager kManager = (KeyguardManager) context.getSystemService(Context.KEYGUARD_SERVICE);
if( kManager .inKeyguardRestrictedInputMode()) {
 //locked
} else {
 //not locked
 }

Next Check for back Button Press event if screen is locked.

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
   //Back Button is pressed
}
return super.onKeyDown(keyCode, event);
}

Catch back button press event when screen locked

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