JetBrains

Shift pressed twice Composite search, can search for file name, class name, variables, methods, etc.
Ctrl + Shift + N Locate / Open files or directories by file name. Add a forward-slash to the end of the input to open a directory.
Ctrl + Shift + F Search for files containing specified content across entire project or specific directories.
Ctrl + Shift + R Replace specified content across entire project or specific directories.
Ctrl + F Find text in current file.
Ctrl + R Replace text in current file.
Ctrl + N Find class file based on the input class name.
Ctrl + F12 Display structure of current file. Can filter using input on pop-up layer.

Ctrl + Z Undo.
Ctrl + Shift + Z Redo.
Ctrl + Y Delete current line or selected lines.
Ctrl + D Copy the current line or selected text and insert it below the current line.
Ctrl + / Comment out the current line.
Ctrl + Shift + / Comment out the selected code block.
Alt + Insert Auto-generate code, such as setObject/getObject methods, constructors, toString(), etc.
Ctrl + J Insert code template.
Ctrl + F4 Close current editing file.
Ctrl + Tab Switch between editing windows. Pressing delete during the switching process closes the selected window.
Ctrl + Alt + L Format code.
Ctrl + Alt + O Optimize imports by deleting unused imports.
Ctrl + Shift + F12 Maximize the editor.
Shift + F6 Rename file/folder.
Ctrl + Alt + Left Arrow Return to previous editing location.
Ctrl + Alt + Right Arrow Go back to previous editing location.

Ctrl + E Display list of recently opened files.
Ctrl + P Display documentation for parameters.
Ctrl + Q Display documentation for the variable/class/method above the cursor (can also be done during auto-suggestion).
Alt + Enter Offer quick fix based on the problem at the cursor position.

Ctrl + G Go to line in current file
Ctrl + U Go to definition of method or interface in parent class
Ctrl + B Go to implementation of method/variable or interface definition under cursor
Ctrl + Left Click Same as Ctrl + B
F2 Go to the next highlighted error or warning location
Ctrl + Alt + F7 Show usage