Java Interview Questions for 2 Years Experience

ArrayList uses a dynamic array: O(1) random access by index, O(n) insertion/deletion in the middle. LinkedList uses doubly-linked nodes: O(1) insertion/deletion at known positions, O(n) random access. Use ArrayList for most cases (better cache locality, less memory). Use LinkedList only when you frequently insert/delete at both ends (implement Queue/Deque). In interviews, always ask about the access pattern before choosing.