Best Java List implementation to return for an empty List?

Question

Many times I'm operating in a function that returns a List type. For many types of errors or certain inputs it is invalid just to return an empty list which I normally do with the following:

return new ArrayList<DataType>();

Is that the best way or is there a better implementation of the List Interface to use for this situation? I should clarify that by "best" way I'm thinking from a performance perspective. I realize that any gains would be rather trivial but the OCD side of me is curious.

What does OCD stands for? Curious here too =)

Evandro Pomatti
– Evandro Pomatti

2015-01-28 23:37:01 +00:00
Commented Jan 28, 2015 at 23:37 — Evandro Pomatti
– Evandro Pomatti, Commented Jan 28, 2015 at 23:37
@BonanzaOne Obsessive Compulsive Disorder.

Elliott Frisch
– Elliott Frisch

2015-01-28 23:43:56 +00:00
Commented Jan 28, 2015 at 23:43 — Elliott Frisch
– Elliott Frisch, Commented Jan 28, 2015 at 23:43

Alexis King · Accepted Answer · 2015-01-28 23:25:07Z

14

There is a method of Collections specifically for this: Collections.emptyList(). This will return an empty, immutable List. You could replace the line in your code with this equivalent:

return Collections.<DataType>emptyList();

edited Jan 28, 2015 at 23:25

answered Jan 28, 2015 at 23:19

Alexis King

44.1k17 gold badges144 silver badges218 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

IcedDante Over a year ago

As of 1.7- I didn't need to parameterize the return type. That is, return new Collections.emptyList() did not generate a warning.

Alexis King Over a year ago

@IcedDante Yes, you shouldn't need to most of the time—the compiler will figure it out for you. I just specified it explicitly for illustrative purposes.

Evandro Pomatti Over a year ago

@IcedDante Emphasizing: it wil return an immutable List. For example, you will get an Exception if you try to add something to the list.

Collectives™ on Stack Overflow

Best Java List implementation to return for an empty List?

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related