When deciding whether to use a LinkedList or an ArrayList in Java, it's important to understand the differences in their performance characteristics and the nature of the operations you expect to perform on the list.
Use LinkedList over ArrayList when:
Frequent Additions and Deletions: If your application involves frequent insertions and deletions in the list, especially at the beginning or in the middle, a LinkedList is more efficient. This is because LinkedList's elements are linked using pointers, and insertions or deletions only require updating the pointers, which is an $$O(1)$$ operation[5][7][19].
Implementing Stack or Queue: LinkedList is ideal for implementing stacks and queues where elements are frequently added or removed from the ends of the list. LinkedList implements the Deque interface, which supports adding or removing elements from both ends efficiently[5][7][19].
Memory Efficiency for Large Elements: If the elements are large and you need to avoid the cost of reallocating and copying elements when the list grows, a LinkedList can be more memory-efficient. This is because ArrayList needs to resize and copy the entire array when it runs out of space[5][7].
Unknown or Variable List Size: If you don't know the number of elements in advance or if the size of the list varies greatly, a LinkedList can handle these changes better. ArrayList, on the other hand, has to resize the backing array, which can be an expensive operation if it happens frequently[5][7].
Non-Random Access Patterns: If your application does not require frequent random access to elements by index, LinkedList can be a good choice. ArrayList provides $$O(1)$$ access time for random access, which is not the case with LinkedList where access time is $$O(n)$$ on average[5][7][19].
