title: Scala equivalent of java.util.ArrayList
body: <p>I am doing a project in Scala, but am fairly new to the language and have a Java background.  I see that Scala doesn't have ArrayList, so I am wondering what Scala's equivalent of Java's ArrayList is called, and if there are any important differences between the Java and Scala versions.</p>
  
  <p><strong>EDIT:</strong>  I'm not looking for a specific behavior so much as an internal representation (data stored in an array, but the whole array isn't visible, only the part you use).</p>