这个小数字在Android Studio中意味着什么？

Question

For a couple of days, now, I've had this weird little number "4" showing up next to my activity_main.xml in the Project pane in Android Studio:

Does anyone know what that little yellow number means??

I've tried hovering the mouse over it to find out but nothing happens.

I've tried searching through my activity_main.xml text for the number 4 to see if that leads to any clues... and also looked through the layout warnings to see whether any particular warning occurs 4 times. But no.

I've also tried Googling terms like:

• "activity_main.xml number next to it"
• "layout xml small yellow number meaning android studio"

...but these searches return billions of unrelated results due to the common basic terms.

Answer 1

It's a bookmark with a mnemonic - Navigate/Bookmarks/Toggle Bookmark with Mnemonic.

For the example in the picture, because it's a number, you can press Ctrl+4 as a shortcut to go there.