concurrenthashmap jdk1.8

ConcurrentHashMap是Java中的一个线程安全的哈希表实现，它可以在多线程环境下高效地进行并发访问。在JDK1.8中，ConcurrentHashMap进行了一些优化，例如使用了CAS操作来实现并发控制，提高了并发性能。同时，它还引入了一些新的方法，例如forEach()和search()等，方便了对哈希表的遍历和搜索操作。总之，ConcurrentHashMap是一个非常实用的数据结构，可以在多线程环境下高效地进行并发访问。

相关问题

ConcurrentHashMap jdk1.8

在jdk1.8的ConcurrentHashMap中，有5个构造方法。这些构造方法中并没有对内部的数组进行初始化，只是对一些变量进行了初始化处理。其中，第一个构造方法是无参构造方法，调用该方法时，默认的数组长度是16。第二个构造方法是传入一个初始容量的构造方法，该方法会根据传入的值计算一个比这个值大的2的幂次方数作为初始容量。第三个构造方法是传入初始容量、负载因子和并发级别的构造方法，该方法会根据传入的值计算一个比初始容量大的2的幂次方数作为初始容量。第四个构造方法是基于一个Map集合构建ConcurrentHashMap，初始容量为16。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
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ConcurrentHashMap JDK1.8

ConcurrentHashMap is a concurrent version of HashMap introduced in Java 1.5 and improved in Java 1.8. It is designed to support high-level concurrency and provides thread-safe operations for concurrent access.

In JDK 1.8, ConcurrentHashMap was enhanced with several new methods and performance improvements. One notable improvement is the introduction of lock striping, which divides the map into separate segments, each with its own lock. This allows multiple threads to update different segments concurrently, reducing contention and improving performance.

Another improvement in JDK 1.8 is the addition of the forEach method, which allows you to perform an action on each key-value pair in the map in parallel. This can be beneficial when you have a large number of entries to process concurrently.

Furthermore, JDK 1.8 introduced the computeIfAbsent and computeIfPresent methods, which allow you to atomically compute values based on keys. These methods provide a convenient way to update the map's values in a thread-safe manner.

In summary, ConcurrentHashMap in JDK 1.8 provides better performance and enhanced functionality for concurrent access compared to its earlier versions.