When to use each Java Collections data structure [duplicate]

Question

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When to use LinkedList over ArrayList in Java? (33 answers)

Closed 8 years ago.

I see that there are a ton of generic data structures provided in Java. They all implement List, so they can be used almost interchangeably, but when would I want to use each? Personally, I stick to LinkedList because it's something I'm "familiar" with. I'm not asking for an explanation of every single structure, but can you explain some of the more common ones and give their uses, as well as compare and contrast the uses of "Vector-like" structures?

Answer 1

It depends on the performance characteristics and behavior you are looking for.

For example in a LinkedList add, delete, and retrieve are O(1), O(1), and O(n), whereas for an ArrayList, the same operations are O(n), O(n), and O(1) if using get(int) and O(n) if using get(Object). However ArrayList uses less memory than LinkedList per entry.

Answer 2

One often uses Vector<type> to add elements to the structure that are part of the same collection, but do not have any relationship to other members (other than being part of the same collection). A LinkedList indicates that there is some sort of ordering that is important among the members of the collection.