Instantiating Objects within Abstract Class or Concrete Class?

[evac-q8r]

I have an abstract class with several member classes in it in addition to the abstract methods

public abstract class AbstractClass{
   protected ClassA classA;
   protected ClassB classB;
   ...
   public abstract void method1( ArgClass arg, ... );
   public abstract void method2( ArgClass arg, ... );
   ...
   public AbstractClass() {
       class A = new ClassA();  // not sure whether I should instantiate these members here
       class B = new ClassB();  // or if I should instantiate them in a derived (concrete) class.
   }
}

public class ConcreteClass extends AbstractClass{
   public ConcreteClass() {
       class A = new ClassA();  // not sure whether I should instantiate these members here
       class B = new ClassB();  // or if I should instantiate them in a superclass (abstract) 
   }
   public void method1( argument )
   {
    ... method2 definition
   }
   public void method1( argument )
   {
    ... method2 definition
   }
}

Can anyone help me with this seemingly simple issue.

Thanks,

EVAC