title: Can I configure Eclipse project to rebuild upon jar modification?
body: <p>It seems that when I rebuild a jar file that one of my Eclipse projects depends upon, Eclipse doesn't notice that the jar has been modified, and doesn't rebuild the project.  I subsequently have to do a manual clean build.</p>
  
  <p>Specifically, I'm building the jar from within Eclipse using the technique given in <a href="https://stackoverflow.com/questions/1062941/build-project-into-a-jar-automatically-in-eclipse/1066223#1066223">this answer</a> and keeping it in a directory outside my workspace projects.  </p>
  
  <p>The reason I am using the jar as a dependency instead of having the main project depend on the second project directly is because the main project is in Java and the jar project is in Scala. I've found the Scala builds to be very slow, so I decided to keep the project closed and manually build the jar from within Eclipse whenever I make changes to the Scala project. </p>
  
  <p>Is this lack of "external jar modification" detection an Eclipse bug/limitation or is there a way to enable this behavior?</p>