On Thu, 25 Aug 2022 13:46:26 GMT, Kevin Rushforth <k...@openjdk.org> wrote:
>> Since `getChildren()` is not final, one can easily override it and return >> null. >> Therefore, this check should still be done here. >> Maybe we even need to check that every child is not null, since again I can >> override `getChildren()` and return a list that allows null. (The default >> implementation in `Parent` throws an exception when adding a null child) >> >> Interestingly, the javadoc of `getChildren()` states that one should call >> the super method when overriding (although this can't be enforced). So this >> is probably a hypothetical case. > > It's definitely a hypothetical case. `getChildren()` is called all over the > place in JavaFX without a null check, so I see no reason for null checks here. Technically correct, although the [doc of `getChildren()`](https://openjfx.io/javadoc/18/javafx.graphics/javafx/scene/Parent.html#getChildren()) specifically says: > Note to subclasses: if you override this method, you must return from your > implementation the result of calling this super method. The actual list > instance returned from any getChildren() implementation must be the list > owned and managed by this Parent. The only typical purpose for overriding > this method is to promote the method to be public. So considering the case that an overriding method will return `null` is not practical. As for a `null` child, I think that that's also not allowed. Considering that a child can be added at most once to a scenegraph, it would mean that only 1 `null` child is allowed. There might be more issues with `null` children. I don't think there's a good reason to check for them. ------------- PR: https://git.openjdk.org/jfx/pull/841
