使用Uint8List而不是List< int>的优势是什么?在Dart中处理字节数组时? [英] What are the advantages of using Uint8List over List<int> when dealing with byte arrays in Dart?

问题描述

我正在编写一个Dart库，在其中我经常处理字节数组或字节字符串.由于Dart没有字节类型也没有数组类型，因此我将List用于所有字节数组.

I'm writing a Dart library in which I'm very regularly dealing with byte arrays or byte strings. Since Dart doesn't have a byte type nor an array type, I'm using List for all byte arrays.

这是一个好习惯吗?我只是最近才发现dart:typed_data包中是否存在Uint8List.显然，该类旨在通过字节数组的转到实现来实现.

Is this a good practice to do? I only recently found out about the existence of Uint8List in the dart:typed_data package. It's clear that this class aims to by the go-to implementation for byte arrays.

但是它有直接的优势吗?

But does it have any direct advantages?

我可以想象它总是对新项目执行检查，以便用户可以确保列表中没有非字节值整数.但是还有其他优点或不同之处吗?

I can imagine that it does always perform checks on new items so that the user can make sure no non-byte-value integers are inside the list. But are there other advantages or differences?

还有一个名为ByteArray的类，但是对于List来说，它似乎是一个效率很低的替代方法.

There also is a class named ByteArray, but it seems to be a quite inefficient alternative for List...

推荐答案

优点应该是Uint8List比普通List消耗更少的内存，因为从一开始就知道每个元素的大小都是一个字节. Uint8List也可以直接映射到基础优化的Uint8List类型(例如，在Javascript中). 列表切片的副本也更容易执行，因为所有字节都是内存中的布局字符串，因此可以通过一次操作将切片直接复制到另一个Uint8List(或等效的)类型.

The advantage should be that the Uint8List consumes less memory than a normal List, because it is known from the beginning that each elements size is a single byte. Uint8List can also be mapped directly to underlying optimized Uint8List types (e.g. in Javascript). Copies of list slices are also easier to perform, because all bytes are laid-out continguos in memory and therefore the slice can be directly copied in a single operation to another Uint8List (or equivalent) type.

但是，能否充分利用此优势取决于Dart中Uint8List的实现情况.

However if this advantage is fully used depends on how good the implementation of Uint8List in Dart is.

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