I want to learn how can I automatically optimize imports after each save as we do Eclipse(save actions).
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
In version 'Ultimate 2016.2' it is:
File > Other Settings > Default Settings > Auto Import > Optimize imports on the fly
First step:
CTRL + SHIFT + A or CMD + SHIFT + A (for mac)
Second step:
Search Optimize imports
Third step:
Switch ON the option
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.