solution:
Today, I accidentally discovered that when Ctrl+Shift+F searches for a certain string in the full text, it is obvious that this string exists in a certain Java file, but this file does not appear in the search results. Later, I searched on the Internet and found that Android Studio has a default limit on the number of results displayed. So I copied the content of the article on the solution for easy reading.
1.Ctrl+Shift+A, then enter Registry
2. Then find this item
3. Just change the value in the picture to a larger value.
4. Then click Close to close the page. Only in this way can the settings be saved, do not click Restore Defaults, that is reset.