title: how to copy SubClass object in BaseClass copy constructor
body: <p>I would like to make copy of SubClass object in BaseClass constructor. I need that the following code execute correctly.</p>
  
  <pre><code>class BaseClass{
      BaseClass() {}
      BaseClass(BaseClass base) {
          //TODO: how to implement?
      }
  }
  
  class SubClass extends BaseClass {    
     SubClass() {}
  }
  
  public class Test {
      public static void main(String[] args) {
  
          BaseClass sub = new SubClass();
          BaseClass subCopy = new BaseClass(sub);
          if (subCopy instanceof SubClass) {
              // need to be true
          }
      }
  }
  </code></pre>
  
  <p>Is it even possible? If yes how can I do it? Else how can I get similar effect?</p>