How does LinkedHashMap differ from HashMap? What ensures the insertion order?

LinkedHashMap differs from HashMap in that it maintains the order of insertion of elements. In HashMap, the order of elements is not guaranteed and can change during operations.

The insertion order in LinkedHashMap is maintained by using a linked list, which stores the order of added elements. Inside LinkedHashMap, each element contains references to the previous and next elements, allowing traversal of the collection to return elements in the order they were added.

Thus, LinkedHashMap combines fast key-based access (like HashMap) with the ordering of elements by insertion.