什么是ArrayList优于Java中的数组？ [英] When is an ArrayList preferable to an array in Java?

问题描述

在Java中什么时候应该使用ArrayList？何时应该使用数组？

解决方案

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• 数组在它们的大小上是不可变的，你不能轻易地删除和删除元素，而使用ArrayList是很简单的


• 数组比ArrayList更快（作为特殊对象直接由JVM处理），并且需要更少的内存


• 数组有一个不错的语法用于访问元素（例如 a [i] vs a.get（i））




• 数组不能很容易地作为ArrayList包装（例如 Collections utils like checkedList ， code>和 unmodifiableList ）


• code> List 你可以轻松地用 LinkedList 交换实现;这个imho是比普通数组最好的优势


• 数组 toString ， equals 和 hashCode 很奇怪，容易出错，您必须使用数组类实用程序

When should I use an ArrayList in Java, and when should I use an array?

解决方案

Some differences:

• Arrays are immutable in their size, you cannot easly remove and element and remove the hole whereas using an ArrayList is straightforward
• Arrays are fast (handled directly by the JVM as special objects) than an ArrayList and requires less memory
• Arrays have a nice syntax for accessing elements (e.g. a[i] vs a.get(i))
• Arrays don't play well with generics (e.g. you cannot create a generic array)
• Arrays cannot be easly wrapped as ArrayList (e.g. Collections utils like checkedList, synchronizedList and unmodifiableList)
• declaring the ArrayList as List you can easly swap implementation with a LinkedList when you need; this imho is the best advantage over plain arrays
• Array's toString, equals and hashCode are weird and error-prone, you must use Arrays class utilities

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