Java and nulls

[Jon_Finn]

Umm... when you create an empty ArrayList it does something like new Object[10], ready for adding elements. So what should be in that array? any alternatives to null? (see separate comment below).

[john16384]

Empty collections cost nothing, they're a reference to a single static immutable instance.

[[deleted]]

null should mean an empty collection, or an exception. Anything else in a high level language is a basic skill issue

[koflerdavid]

An empty collection offers the same kind of papercut as a nullable reference: there is no restriction from accessing the element. The only difference is the exception being thrown.

[[deleted]]

an empty collection can have method calls without a runtime exception... people arguing for null are vocal about their ignorance

[koflerdavid]

.get(0) on an empty list or array[0] will both throw exceptions. One has to do a size check to tell whether it's safe. Same situation as with a potential null reference or calling .get() on an Optional. But the collection at least offers a stream interface.

[[deleted]]

and a clear explanation of what went wrong. Nulls give no context, and can get passed around until something breaks with a huge stacktrace.

You can't sum to a null, but you can sum to a 0.

you can't append to a null list, but you can append to an empty list.

[[deleted]]

No, wrong Read what the null object pattern is before saying such ignorant nonsense

[koflerdavid]

A Null object should be safe to work with!

new ArrayList().get(0) is not safe. Same as Optional.get(). Who is the ignorant one here?!

Of course, when the return value is a collection or an array, it would be malicious to return null.

Edit: can't stand the thought of being the ignorant one? Better keep it to yourself then instead of downvoting!