ArrayList vs. LinkedList in Java: Performance Comparison & When to Use
ArrayList is a Java class that stores elements in a contiguous, resizable array; LinkedList is a doubly-linked chain of nodes, each holding an item plus references to neighbors.
Devs pick ArrayList for everyday collections, then switch to LinkedList when they picture lightning-fast inserts. In reality, the cache-friendly array often wins, so the confusion lingers like a stubborn urban legend.
Key Differences
ArrayList shines at O(1) random access but pays O(n) for middle inserts. LinkedList inserts and deletes in O(1) once you reach the node, yet O(n) to get there. Memory overhead is 1–2 extra pointers per element in LinkedList.
Which One Should You Choose?
Use ArrayList for frequent reads and appends. Choose LinkedList only when you constantly add/remove at both ends or need a queue/stack without extra wrappers. Benchmark before trusting myths.
When does LinkedList actually beat ArrayList?
In deque-style workloads—constant add/remove at head and tail—LinkedList avoids costly array copies.
Can I mix ArrayList and LinkedList in one project?
Absolutely; pick the right tool per task. A GUI list model might be LinkedList, while cached data stays in ArrayList.