After an inactive period, setting your smartphone to a locked mode is the simplest way to prevent would-be thieves from stealing your personal information through opportunistic and unauthorized access.

Switch Off and Lock screen is a free application that will lock your screen.

With Switch Off and Lock screen, you can lock your screen with a single tap, and you can reduce the number of times you press the power button to extend the life of your device.

Important Notice:
Before uninstalling, go to "Settings" -> "Security" (or "Location & security") -> "Device Administrators" and uncheck the ‘Switch Off and Lock screen’ app.”