How to retain all instances of of a single subclass from a general ArrayList
<p>I'm having a problem and I can't figure out a clean solution.</p>

<p>I have this superclass "Creature" with subclasses "Human" and "Zombie"
I have constructed a series of humans and zombies and saved them in an ArrayList
Now I want to get the subArrayList that only contains the constructed humans.
I thought I could use the "retainAll" but it turns out it doesn't do what I thought it would do.</p>

<p>Any suggestions how to create a new ArrayList with only the objects of subclass Zombie in it?</p>
