Java – internal class extension

In Java, I have the following classes:

public class A{
  protected class B{
  }
}

Can internal classes be extended in the following ways?

public class C extends A{
  protected class D extends B{
  }
}

What I want to do is that I have class C above. I need to change the internal class of a, so I think I need to extend the internal class to do it, but I don't know how to do it

Solution

According to this page, you have the right way to expand internal courses Some tips on this can be found here (search for "extension")