title: Using Bag in Java
body: <p><a href="http://commons.apache.org/proper/commons-collections/javadocs/api-2.1.1/org/apache/commons/collections/Bag.html" rel="nofollow">Here</a>, I see that <code>Bag</code> class should be in <code>java.util.Collection</code> but when I try to use it, I get <code>cannot be resolved to a type</code> error.</p>
  
  <p>Should I copy+pase <a href="http://algs4.cs.princeton.edu/13stacks/Bag.java.html" rel="nofollow">this</a> or is there some library missing?</p>