title: Properties Class vs System Properties
body: <p>I just read that it is possible to store key/value pairs (properties) using the <code>Properties</code> class, which is a subclass of the <code>HashTable</code>. However, I have also read that you can store properties directly using <code>System.setProperty</code>. </p>
  
  <p>So which one do I use? What are the real use-cases of each?</p>
  
  <p>Much appreciated.</p>