Java LinkedList method notes

Last updated: 28 Sept 20263 min read

tutorial

LinkedList method choice depends on the endpoint, the empty-case contract, and whether removal targets a value or an index.

Endpoint pairs

FIFO: offer or addLast, then poll or pollFirst.
LIFO: push, then pop; pop throws when empty.
Read without removing: peekFirst or peekLast returns null when empty.
Strict endpoint read: getFirst or getLast throws when empty.
Position: remove(int) returns an element.
First equal value: remove(Object) returns a boolean.

Costs

Endpoints use O(1) link work. Searching and arbitrary indexing are O(n) in the worst case. A full iterator traversal is O(n). A get(index) loop over the entire list can be O(n²). Each element requires linked-node storage.

Connected lessons

Continue with Java LinkedList: operations, internals and failure cases, Java LinkedList quiz.

Common Mistakes

Null elements make poll and peek results ambiguous. The class does not coordinate access between threads. A shallow copy preserves references to mutable elements.

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