why the following code is wrong in Java?
List<List<Integer>> list = new ArrayList<ArrayList<Integer>>();
I know List<List<Integer>> list = new ArrayList<List<Integer>>() is correct.
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villion
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2(The duplicate is actually simpler, because it's not "doubly generic" like this one is - but if you understand that, you can apply it to this easily. Basically, consider what `list.add(new LinkedList
())` is doing to an object which was created as (and may still be *referenced* as) `ArrayList – Jon Skeet Mar 25 '15 at 20:56>`.) -
This has been asked several times in the past. In fact, @JonSkeet has answered it more than once. His answer [here](http://stackoverflow.com/q/2745265) is, in my opinion, better than his answer in the one that he closed this as a duplicate of, despite how much I _loathe_ having `Dog extends Animal` as an example in any question about inheritance. – Dawood ibn Kareem Mar 25 '15 at 21:54
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Because generic types in Java are not covariant.
Filip Roséen - refp
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Crazyjavahacking
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It was marked as duplicate, please follow the linked questions. – Crazyjavahacking Mar 25 '15 at 21:05