When does Android destroy activity without destroying the entire process?

Question

I want to understand and simulate when does Android call onDestroy() of my activity, without destroying the entire process. I'm not calling finish(), and I want to make Android destroy my activity on it's own.

From the activity-lifecycle documentation:

The system never kills an activity directly to free up memory. Instead, it kills the process in which the activity runs, destroying not only the activity but everything else running in the process, as well.

But the Android Activity documentation says:

This (onDestroy) can happen because [...] the system is temporarily destroying this instance of the activity to save space.

So which one is it? Does Android destroy activities when it's low on memory, or does it only kill entire processes?

I want to simulate a situation where Android kills the activity without killing the entire process. I can mimic this by using the "Don't keep activities" developer-mode setting, but I want to understand how can this happen in the real-world.

Answer 1

I want to make Android destroy my activity on it's own.

Android does not do that, other than through your actions (e.g., finish()) or user actions (e.g., BACK navigation, configuration changes).

So which one is it?

The former (Android kills processes, not activities). See this answer from the woman who wrote this stuff. FWIW, also see this decade-old blog post of mine.