title: can not use javafx on intellij idea
body: <p>I have problem importing import "javafx.util.Pair" into my program. 
  after searching the net I've found this answer <a href="https://stackoverflow.com/questions/27178895/cannot-resolve-symbol-javafx-application-in-intellij-idea-ide">cannot resolve symbol javafx.application in IntelliJ Idea IDE</a> and I've installed desired jar file but still I've problem to import.
  this is what I face to when open java jdk.
  I don't know the why the "jfxrt.jar" is different.
  <a href="https://i.stack.imgur.com/MoqlS.png" rel="nofollow noreferrer">note the black arrow on the folder icon</a> </p>