IntelliJ IDEA displays an intention action alert, and it is your task to define which action (if any) should be performed.

To apply an intention action
  1. Click the light bulb icon, or use the ⌥⏎ or ⌥⏎⌥⏎ or ⌥⏎⌘1 or ⌘1⌥ Enter, ⌥⏎ or ⌥⏎⌥ Enter, ⌥⏎ or ⌥⏎ keyboard shortcut to bring up the suggestion list.
  2. Click the desired option, or use the arrow keys to select the option and press or or or Enter, or Enter, ^ M, , ⌃M, or ⌃M.

See Also

Reference: