Shulou(Shulou.com)05/31 Report--

What is the significance of HashMap? in view of this question, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way.

I have been thinking about a question: what is the meaning of HashMap? In other words, why did Java design HashMap?

HashMap can store a collection of key-value pairs and make quick lookups.

For quick lookups, HashMap chooses arrays instead of linked lists. The search efficiency of O (1) complexity is realized by using the index of the array.

In order to make use of index lookup, HashMap introduces the Hash algorithm to map key to array subscript: key-> Index.

The introduction of Hash algorithm leads to Hash conflict.

In order to resolve Hash conflicts, HashMap uses the chain address method and changes to linked list storage at the conflict location.

Too many nodes in the linked list lead to the deterioration of the lookup performance of the nodes on the linked list.

In order to optimize the lookup performance, HashMap transforms the linked list into a red-black tree after the length of the linked list exceeds 8, in order to improve the search efficiency of O (n) complexity to O (log n).

The meaning of the existence of HashMap is to achieve a fast search and insert and delete performance of a K _ key/value data structure.

The answer to the question about the significance of HashMap is shared here. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel to learn more about it.

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