override pattern lock to display toast

Question

Is is possible that a toast will get displayed of my application overriding every kind of lock in the device that exist when user press the power button twice in unrooted device. I am just few months old to android.

Answer 1

There isn't a way to override the lock screen but there is a way to co-operate with it. Starting from Android 4.2, you can write a lock screen widget to display custom information on the lock screen.

Answer 2

Update:

Only Android versions lower than 5.0 support lock-screen widgets. For Android 5.0 and higher, only home_screen is valid.

Source: API Docs