Introducing self containing objects (Node)
The sample is not "defining something with itself." Rather it is defining two different kinds of things.

The first line: public class Node&lt;T&gt; { is beginning the definition of a template for things to be made later. That definition will be handled at compile time. The third line: Node&lt;T&gt; next; sets up an object that will be instantiated using some template. Later in the compile process, when the object is created, Java will look in the table for the template called "Node" that can handle some type. Since, by then, the complete template will exist, there's no problem. The key point here is that next is not a template, it is object that will use the Node&lt;T&gt; template when it is created.

If you also define public class Node2&lt;T&gt; extends Node&lt;T&gt;, then at run time, next could refer to the template Node&lt;T&gt;, or the template Node2&lt;T&gt;. Exactly which it is will be determined when the next object is instantiated.

If it hasn't already been covered, that would be an opportune time to cover early and late binding.