How do I know that the app goes to the background on Android and then comes to the foreground?

The onPause() and onResume() methods are invoked when the app goes to the background or returns to the foreground. However, these methods are invoked when the application is first created and immediately before it dies.

There is no direct way to know the status of the application in the background or foreground, but in this case, onWindowFocusChanged(boolean hasFocus) may be used. OnWindowFocusChanged is If this activity is shown on the screen, hasFocus returns true, otherwise false.