title: Why does the java.util.Set<V> interface not provide a get(Object o) method?
body: <p>I understand that only one instance of any object according to .equals() is allowed in a Set and that you shouldn't "need to" get an object from the Set if you already have an equivalent object, but I would still like to have a .get() method that returns the actual instance of the object in the Set (or null) given an equivalent object as a parameter. </p>
  
  <p>Any ideas/theories as to why it was designed like this?</p>
  
  <p>I usually have to hack around this by using a Map and making the key and the value same, or something like that.</p>
  
  <p>EDIT: I don't think people understand my question so far. I want the exact object instance that is already in the set, not a possibly different object instance where .equals() returns true.</p>
  
  <p>As to why I would want this behavior, typically .equals() does not take into account all the properties of the object. I want to provide some dummy lookup object and get back the actual object instance in the Set.</p>