Java – why is it faster to iterate buckets in linked HashMap than HashMap?

It's hard for me to understand that

Google search, I found

and

If this is the case, why does the only HashMap have to iterate over empty buckets instead of LinkedHashMap, although both are implemented using the same bucket concept? All entries are doubly linked, meaning "all buckets and elements are doubly linked", or just "elements are doubly linked"

Please give me a diagram to explain the implementation of bidirectional link bucket in LinkedHashMap

Thank you in advance

Solution

The LinkedHashMap bucket node (entry) holds two additional pointers (before and after) to maintain order

This is the structure at creation time

Map<Integer,String> linkedHashMap = new LinkedHashMap<Integer,String>();

Now let's add an element

linkedHashMap.put(1,"obj1");

This is before the LinkedHashMap header, followed by the entry object

Let's add another element

linkedHashMap.put(15,"obj15");

Check the change of the pointer with the previous state of red

Let's add another element

linkedHashMap.put(4,"obj4");

When another entry inserts the same hash, the next pointer in each entry forms singlelikedlist