title: Java call method of descendant class in abstract superclass
body: <p>I have a big method doComplicateCalculation in abstract class - AbstractClass.
  Also have small class Descendant that extends AbstractClass.</p>
  
  <p>I need to introduce in method doComplicateCalculation small changes like:</p>
  
  <pre><code>..............
  if (val&lt;0){
     continue;
   }
  ..................
  </code></pre>
  
  <p>The problem also more difficulta that big method in internal class of abstract class.
  How it can be done?
  Thanks.</p>