title: Java - When limited to built-in packages, what is the best way to store data in an external file?
body: <p>I'm really struggling to find any concrete information on how to store data in an external file, when limited to built-in Java packages.</p>
  
  <p>My coursework limits me to not use any third party packages, otherwise I would have used Gson or some other JSON manager, or SQLite.</p>
  
  <p>Which built-in package would you recommend to someone who is new to Java?</p>