Why wont this assignment work?

Question

I\'ve got a class Results which extends ArrayList. I\'ve got an object i which has a function i.getResults() w

Answer 1

You have

  Results extends ArrayList

So anywhere you might use ArrayList you can use Results, but not vice-versa. When you say extends you are saying I can do everything he can do, and a little bit more.

  C extends D

says: if all you need is a D then you can use either a C or a D. But someone needing a C cannot accept a D, because it doesn have all the capabilities C offers.