What is Eclipse's Ctrl+O (Show Outline) shortcut equivalent in IntelliJ IDEA?

I haven't used Eclipse for years, so I'm not that familiar with the behaviour you're after - but I believe Ctrl + F12 may do what you want: it is the shortcut for the File structure Popup in the default mapping.

Shortcuts:

• Mac: ⌘+F12
• Windows: Ctrl+F12
• Ubuntu/CentOS: Ctrl+F12

Above works on IntelliJ versions 14 to 2020.

Windows : ctrl + F12

MacOS : cmd + F12

Above commands will show the functions/methods in the current class.

Press SHIFT TWO times if you want to search both class and method in the whole project.