purpose
import [library] to [intellij]
What is library?
pre-made code collection that you can use it right away. It help people to develop program quickly.
Steps
download library file (jar file)
File -> Project Structure
Modules -> project -> Dependencies of tabs
click “+”(=JARs or directories…) to select the jar file that you want to import.
left side bar underExternal Libraries, you will see imported library.