title: What's the fastest way of converting a collection to an array on Android?
body: <p>In Java, for ages, when you wanted to convert a Collection into an array you did this: <code>coll.toArray(new ItemObject[coll.size()])</code>. However, in Android Studio I got a warning. Here's the full text of the warning's explanation as provided by Android Studio:</p>
  
  <blockquote>
    <p>There are two styles to convert a collection to an array: either using
    a pre-sized array (like <code>c.toArray(new String[c.size()])</code>) or using an
    empty array (like <code>c.toArray(new String[0]</code>). In older Java versions
    using pre-sized array was recommended, as the reflection call which is
    necessary to create an array of proper size was quite slow. However
    since late updates of OpenJDK 6 this call was intrinsified, making the
    performance of the empty array version the same and sometimes even
    better, compared to the pre-sized version. Also passing pre-sized
    array is dangerous for a concurrent or synchronized collection as a
    data race is possible between the size and toArray call which may
    result in extra nulls at the end of the array, if the collection was
    concurrently shrunk during the operation. This inspection allows to
    follow the uniform style: either using an empty array (which is
    recommended in modern Java) or using a pre-sized array (which might be
    faster in older Java versions or non-HotSpot based JVMs).</p>
  </blockquote>
  
  <p>But this explanation is only considering HotSpot, the Java VM, so I wonder: Is this warning also valid for Android? Are those improvements mentioned above also implemented? What would be the fastest way of converting a collection to an array on Android?</p>
  
  <p>EDIT: I know it doesn't matter a lot nowadays, still I'd like to know. =)</p>