intellij.md

IntelliJ-cheatsheet

Most used

Double shift     | Search everywhere
Alt + Enter      | Show intention actions and quick-fixes
Ctrl + w         | Select current word (Extend selection)
Ctrl + Shift + W | Shrink selection 
Ctrl + E         | Show recent files popup 
Shift + F6       | Rename (refactor)

Editing

Ctrl + /          | Comment /uncomment with line comment 
Ctrl + Alt + L    | Reformat code
Ctrl + Alt + O    | Optimize imports
Ctrl + Alt + I    | Auto-indent line(s) 
Tab / Shift + Tab | Indent /unindent selected lines Tab / Shift + Tab
Ctrl + D          | Duplicate current line
Ctrl + Y          | Delete line
Ctrl + w          | Select current word (Extend selection)
Ctrl + Shift + W  | Shrink selection 
Ctrl + Shift + J  | Join lines
Shift + Enter     | New line (no matter where the caret is)
Ctrl + Delete     | Delete to word end 
Ctrl + Backspace  | Delete to word start 

Navigation

Ctrl + G                   | Go to line
Ctrl + E                   | Open recent files popup
Ctrl + B / Ctrl + click    | Go to declaration
Ctrl + Alt + B             | Go to implementation
Ctrl + Alt + H             | Call hierarchy
Ctrl + Alt + <Left arrow>  | Navigate back
Ctrl + Alt + <Right arrow> | Navigate forward

Multiple cursors

Ctrl + (Ctrl + Up)      | Add carets above the current caret using keyboard
Ctrl + (Ctrl + Down)    | Add carets below the current caret using keyboard
Shift + Ctrl + Alt + J  | Add cursor at search results (selection)
Alt + J                 | Add cursor at next occurrence

Official JetBrains cheatsheet