How do the main operations of ArrayList and LinkedList differ in execution time?

The main differences in time complexity between ArrayList and LinkedList are due to their data structures:

• ArrayList is based on a dynamic array, so:

  • Fast index access — O(1).
  • Insertion or deletion in the middle — O(n), because elements need to be shifted.

• LinkedList is implemented as a doubly linked list:

  • Index access — O(n), traversal needed.
  • Insertion and deletion in the middle — O(1), if the node reference is known.

Therefore, if fast random access is often needed — ArrayList is better. If frequent insertions/deletions in the middle are required — LinkedList may be more efficient.