Application not open main activity when it was killed after pressing home button in android

Question

In my Application, activity A is launcher activity, from A it called B and from B it called C, I have such more than 5 activities. In C when I press home button, and again o

Answer 1

Pressing the Home switches you from the app to the home screen, whilst leaving your app running in the background.

Except that when your phone is running low on resources like memory it will start to close apps that are running in the background, so that your phone has enough resources for what you're trying to do now. Games are often amongst the first apps the phone will "kill" to save resources as they often use a lot more memory and CPU than other apps. This is why sometimes your game is stil lrunning paused, and sometimes Android has closed it for you.