Guide and performance analysis of the HashSet in Jin Collections

Guide and performance analysis of the HashSet in Jin Collections Hashset is one of the collection classes commonly used in Java programming language. It implements SET interface to store elements that do not repeat.In Jin Collections, HashSet is an important tool for element storage and retrieval.This article will introduce the basic usage of HashSet and analyze its performance. Basic usage of hashset Create a Hashset object: HashSet<String> set = new HashSet<>(); Add elements: set.add ("Element 1"); set.add ("Element 2"); set.add ("Element 3"); Removal element: set.remove ("Element 2"); Check whether the element exists: boolean contains = set.contains("元素1"); Get the size of Set: int size = set.size(); Traversing Hashset: for (String element : set) { System.out.println(element); } Hashset performance analysis HashSet's performance is mainly affected by two factors: initial capacity and load factor. The initial capacity is the size of the storage space assigned by Hashset when creating.When the number of elements in Hashset exceeds the initial capacity, HashSet will automatically increase the capacity and re -calculate the hash code.Therefore, if the initial capacity is set too small, it may cause continuous capacity adjustment to reduce performance.Generally speaking, the selection of initial capacity shall make reasonable estimates based on the expected number of elements. The load factor is a parameter used to determine when to perform capacity adjustment.When the number of elements in the hashset reaches the volume of the capacity and the load factor, the capacity adjustment operation will be triggered.The value range of the load factor is between 0.0 and 1.0, and the default value is 0.75.Low load factor can reduce the probability of conflict, but increase space overhead.Higher load factor can save space, but may lead to increased conflict.The selection of load factor should weigh the space efficiency and time efficiency. In addition to the initial capacity and load factor, the performance of HashSet is also related to the implementation of the hash function.For most scenarios, the default hash function provided by Java can usually provide better performance.However, if the calculation of the hash code of the element is more time -consuming, you can customize the hash function to improve performance. It should be noted that HashSet is disorderly and does not guarantee that the storage order of elements is consistent with the order of addition. In summary, Hashset is an important collection class in Jin Collections, which provides efficient element storage and retrieval operations.When using HashSet, you need to reasonably choose the initial capacity and load factor, and choose the appropriate hash function according to actual needs to obtain better performance. It is hoped that this article will be helpful to understand the use of HashSet's usage and performance analysis.