title: Is there a difference between Map and Hashmap?
body: <p>I've seen people use Map instead of HashMap to declare a HashMap.</p>
  
  <p>e.g. <strong>Map mapName = new HashMap();</strong>
  Whereas I'd normally use <strong>HashMap mapName = new HashMap();</strong>;</p>
  
  <p>The same for a a HashSet, I've seen <strong>Set setName = new HashSet()</strong>;  used,
  whereas I'd normally use a <strong>HashSet setName = new HashSet()</strong></p>
  
  <p>Same for ArrayList (List) and so on.</p>
  
  <p>My question is, is there any benefit to doing this, or is it just a matter a perspective?</p>