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java hashMap

时间: 2023-11-12 20:29:34 浏览: 81

Java HashMap

Java HashMap Java 集合框架 HashMap 是一个散列表，它存储的内容是键值对(key-value)映射。 HashMap 实现了 Map 接口，根据键的 HashCode 值存储数据，具有很快的访问速度，最多允许一条记录的键为 null，不支持线程同步。 HashMap 是无序的，即不会记录插入的顺序。 HashMap 继承于AbstractMap，实现了 Map、Cloneable、java.io.Serializable 接口。 HashMap 的 key 与 value 类型可以相同也可以不同，可以是字符串（String）类型的 key 和 value

HashMap is a class in Java that implements the Map interface. It stores key-value pairs and allows efficient retrieval of values based on their corresponding keys. In other words, it maps unique keys to associated values. HashMap uses hashing techniques to store and retrieve elements. When an element is added to the HashMap, a hash code is generated for its key. This hash code is used to find the index of the bucket in which the element will be stored. If two keys have the same hash code, they will be stored in the same bucket, and the HashMap will use an internal linked list to store them. HashMap is widely used in Java programming due to its efficiency in retrieving elements. It has a constant time complexity of O(1) for put and get operations, making it ideal for large datasets. However, it does not guarantee the order of the elements and is not thread-safe by default. To ensure thread-safety, ConcurrentHashMap can be used instead.

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