How to optimize imports automatically after each save in IntelliJ IDEA

Solution 1:

IntelliJ IDEA offers an option to Optimize imports on the fly in Settings | Editor | General | Auto Import and Optimize imports option in the Commit Project dialog.

Solution 2:

The mentioned answer works, but there is also the Intellij "save actions" plugin available from the JetBrains plugin repository that does that (as well as other things): Intellij Save Actions Plugin.

Installation

File > Settings > Plugins > Browse repositories... > Search 'Save Actions' > Category 'Code tools'

Disclaimer

I'm the plugin developer

Solution 3:

First step:

CTRL + SHIFT + A or CMD + SHIFT + A (for mac)

Second step:

Search Optimize imports

Third step:

Switch ON the option