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copied!<p>Let me start with example:</p> <pre><code>List<DoesStuff> a = new LinkedList<DoesStuff>; LinkedList<DoesStuff> b = new LinkedList<DoesMoreStuff>; //doesn't work. </code></pre> <p>In the second example if it was legal, you would be able to add <code>DoesStuff</code> objects into list of <code>DoesMoreStuff</code>.</p> <p>The trick is in your <code>DoesMoreStuff</code> you have type Paramter <code>E</code> which is not used and you've already explicitly set type parameter and have these methods:</p> <pre><code>public void MethodA(ArrayList<DoesMoreStuff.ElementA> moreElements) {} public void MethodB(ArrayList<DoesMoreStuff.ElementA> moreElements) {} </code></pre> <p>you can't overide them like this as described in the example above</p> <pre><code>@Override public void MethodA(ArrayList<E> moreElements) {} // as described in the example above </code></pre> <p><strong>Now coming to the third class:</strong></p> <pre><code>public class DoesEvenMoreStuff extends DoesMoreStuff<DoesEvenMoreStuff.ElementB> </code></pre> <p>type parameter <code>DoesEvenMoreStuff.ElementB</code> set <code>E</code> type parameter in superclass which is not used.</p> <p>Super class has these methods which you can override without changing type paramters as in the example in the beginning.</p> <pre><code>public void MethodA(ArrayList<DoesMoreStuff.ElementA> moreElements) {} public void MethodB(ArrayList<DoesMoreStuff.ElementA> moreElements) {} </code></pre> <p>Hope that helped to clarify things.</p>

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