title: Properly import a class in BlueJ
body: <p>I've used JDatePicker for  a simple app, but my teacher said that he will accept no precompiled .jar's, and he needs to see how it's able to compile from just sources.<br>
  So I checkout JDatePicker source code, extract it, and add every <code>.java</code> file from the extracted directory to my BueJ project. I had to remove some imports inside those extracted classes, so that JVM will "look inside project".<br>
  Now BlueJ can not find where classes <code>JDatePickerImpl</code> &amp; <code>JDatePanelImpl</code> are defined...<br>
  And neither can I. If I <code>grep -rn</code> through project folder all I get is two lines of my own code.<br>
  Can anybody suggest how to import classes that are supposed to be there, just can't find definitions? Maybe, I should write an "implementation" (hence the <code>Impl</code> in name)?</p>
  
  <p>Here's <a href="https://github.com/mekkanizer/TrainTicket" rel="nofollow noreferrer">uploaded project</a><br>
  The only file written by me is <code>TrainTicket.java</code></p>