title: Java: Is there a container which effectively combines HashMap and ArrayList?
body: <p>I keep finding a need for a container which is both a <code>HashMap</code> (for fast lookup on a key type) and an <code>ArrayList</code> (for fast access by integer index). </p>
  
  <p><code>LinkedHashMap</code> is almost right, in that it keeps an iterable list, but it is unfortunately a <em>linked</em> list... retrieving the Nth element requires iterating from 1 to N.</p>
  
  <p>Is there a container type which fits this bill and which I've somehow missed? What do other people do when they need to access the same set of data by key <em>and</em> by index?</p>