Extending multiple classes

Question

I know Java doesn't support multiple inheritance by not allowing to extend more than one class. I just want to know if there is a workaround for my issue.

I've a class named CustomAction which needs to extend two abstract classes, BaseAction and QuoteBaseAction. I can't change any of these abstract classes and make one extend other.

These abstract classes have method implementations which I need to make use of. I can't create an interface also since an interface can extend only another interface.

Any ideas?

Answer 1

Here you go ...

public class CustomAction extends BaseAction {
  class Inner extends QuoteBaseAction {

  }
}

Answer 2

Composition is the way to go.Make one of your abstract class as part of your class.

public abstract class Abs1 {
 //
 } 
public abstract class Abs2 {
 //
 } 
public  class Main extends Abs1 {
 Abs2 abs2 = ...
//impl
 }