title: Finding out the names of files in a directory
body: <p>I am exporting objects in serializable form to the directory containing the src, build files. there are groups which share the start of their filenames, e.g.</p>
  
  <pre><code>lounge - 1,0
  lounge - 2,4
  dining room - 3,5
  dining room - 4,6
  dining room 5,2
  </code></pre>
  
  <p>I need to make an array list of all the groups so in this case an array containing lounge and dining room. Can anybody help?</p>