Shulou(Shulou.com)06/02 Report--

The main content of this article is to explain "what is HashMap". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn what HashMap is.

1. Brief introduction to HashMap

HashMap is the most common collection class in Java. It is based on the hash algorithm. The implementation of HashMap is not synchronous, which means that it is not thread-safe.

2. HashMap data structure

Before JDK1.8, HashMap was implemented using array + linked list. After JDK1.8, in order to optimize the longer linked list, the red-black tree was introduced, and the data structure became array + linked list + red-black tree. For why you want to use a red-black tree, please refer to https://dwz.cn/nPFXmXwJ

When the value of the linked list exceeds 8, it is converted to a red-black tree.

At this point, I believe you have a deeper understanding of "what HashMap is", might as well come to the actual operation of it! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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