I have developed an Android desktop. There are many buttons on the desktop. Clicking each button will enter a different Activity. At this time, when you open the background cleaning interface of the phone, you will see that these Activities are also presented one by one. What is the reason for this? This problem causes problems when opening some other apps. For example, before opening an app, a newly opened Activity will always flash. . 
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Let’s take a look at this. I don’t have time to verify the question, so I’ll just give you the document and read it carefully. I didn’t verify it before and answered others based on my impression, but I got the wrong answer. It was a misunderstanding