Which array traversal method — ArrayList or LinkedList — processes 100 million elements faster?

To iterate over 100 million elements in Java, it is faster to use ArrayList.

The reason is that ArrayList is based on an array, and access to elements by index occurs in constant time O(1). When iterating with an iterator or a for loop with an index, sequential access to elements in memory is efficient in terms of caching.

LinkedList, on the other hand, is implemented as a doubly linked list, where access to an element by index requires traversing the list from the beginning or end, which takes O(n) time for each access. Even when using an iterator, LinkedList has more overhead due to storing links and frequent memory jumps.

Therefore, for large data volumes and frequent iteration, ArrayList is preferable.