在什么情况下CopyOnWriteArrayList适合？

问题描述

我正在了解类。 / p>

• 复制新数组的目的是什么？


• 是否为其他线程读取array？

因此，如果系统具有高并发性，并且大多数线程的操作都读取不写入， code> CopyOnWriteArrayList

解决方案

如：

是一个在Java 5中引入的并发Collection类并发API以及它的流行的表兄弟ConcurrentHashMap在Java。

CopyOnWriteArrayList实现了List接口，如ArrayList，Vector和LinkedList，但它是一个线程安全的集合，它以一种稍微不同于Vector或其他线程安全的方式实现了线程安全，安全集合类。

要获得最新版本，像 list.iterator（）;

话虽如此，更新这个集合alot会杀死性能。如果你试图对一个CopyOnWriteArrayList排序，你会看到列表抛出一个UsupportedOperationException（排序调用集合集合N次）。您应该在进行超过90 +％的读取时使用此读取。

I am learning about the CopyOnWriteArrayList class.

• What is the purpose of copying a new array?
• Is it for other threads to read the array?

So if a system has high concurrency and most of the threads' actions are reading not writing, it is better to use CopyOnWriteArrayList.

解决方案

As stated on this link:

CopyOnWriteArrayList is a concurrent Collection class introduced in Java 5 Concurrency API along with its popular cousin ConcurrentHashMap in Java.

CopyOnWriteArrayList implements List interface like ArrayList, Vector and LinkedList but its a thread-safe collection and it achieves its thread-safety in a slightly different way than Vector or other thread-safe collection class.

To get the most updated version do a new read like list.iterator();

That being said, updating this collection alot will kill performance. If you tried to sort a CopyOnWriteArrayList you'll see the list throws an UsupportedOperationException (the sort invokes set on the collection N times). You should only use this read when you are doing upwards of 90+% reads.

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