个人常用：

Ctrl + N 查找类
Ctrl + Shift + N 查找文件（包括类） 
Ctrl + Shift + F 查找包含输入字符的文件
双击Shift  Search Everywhere
Ctrl + Shift + L 格式化代码   
Ctrl + I    Implement methods
Ctrl + G    Go to line
Ctrl + Alt + B  Go to implementation(s)
Ctrl + Alt + V  Extract Variable 
Ctrl + Alt + M  Extract Method

以下使用较少：

Ctrl + O    Override methods
Ctrl + Alt + T  Surround with… (if..else, try..catch, for, synchronized, etc.)

Ctrl + Shift + J    Smart line join 两行拼接成一行
Alt + Right/Left    Go to next/previous editor tab

F12     Go back to previous tool window
    
Ctrl + E    Recent files popup
Ctrl + Shift + Backspace    Navigate to last edit location
Ctrl + Shift + B    Go to type declaration

Ctrl + ] / [    Move to code block end/start    
Ctrl + F12  File structure popup

Ctrl + Alt + F  Extract Field
Ctrl + Alt + C  Extract Constant

Alt + Shift + C   View recent changes

Ctrl + J   Insert Live Template

Ctrl + Alt + S  Open Settings dialog

Ctrl + Tab  Switch between tabs and tool window