Question

I have tree classes e.g. ClassA, ClassB, ClassC. ClassA and ClassB extends ClassC. I have two Multimaps – Multimap<Integer, ClassA> and Multimap<Integer, ClassB> and I would like to merge this two multimaps into one. I have tried find some solution but unsuccessfully. I have tried sth. like Multimap<Integer, ? extends ClassC> but I don’t know if I make it right and if I can merge two multimaps together. Can someone help me? Thank you for response, I appreciate every help.

Answer 1

Multimap<Integer, ClassC> combine(Multimap<Integer, ? extends ClassC> a, Multimap<Integer, ? extends ClassC> b) {
  Multimap<Integer, ClassC> combined = new SetMultimap<Integer, ClassC>();  // or whatever kind you'd like
  combined.putAll(a);
  combined.putAll(b);
  return combined;
}