title: default Collection type
body: <p>Assume you need to store/retrieve items in a <code>Collection</code>, don't care about ordering, and duplicates are allowed, what type of <code>Collection</code> do you use?</p>
  
  <p>By default, I've always used <code>ArrayList</code>, but I remember reading/hearing somewhere that a <code>Queue</code> implementation may be a better choice. A <code>List</code> allows items to be added/retrieved/removed at arbitrary positions, which incurs a performance penalty. As a <code>Queue</code> does not provide this facility it should in theory be faster when this facility is not required.</p>
  
  <p>I realise that all discussions about performance are somewhat meaningless, the only thing that really matters is measurement. Nevertheless, I'm interested to know what others use for a <code>Collection</code>, when they don't care about ordering, and duplicates are allowed, <strong>and why</strong>?</p>