Android: making a fullscreen application

Question

What is the simplest change that I can make to a new Blank Activity, as created by the latest version of Android Studio, to get the app to appear fullscreen?

I want

Answer 1

Add these to Activity of your application.

Android JAVA

getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
  WindowManager.LayoutParams.FLAG_FULLSCREEN)

;

Android Kotlin

supportActionBar?.hide()
window.setFlags(
WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN
)