Flutter:不推荐使用列表? [英] Flutter: List is deprecated?

问题描述

升级到最新版本的 flutter 后，我的所有列表都收到了弃用警告.

After upgrading to the latest version of flutter, I get a deprecation warning for all my Lists.

List<MyClass> _files = List<MyClass>();
=>'List' is deprecated and shouldn't be used.

不幸的是，它没有提示用什么来替换它.那么我们现在应该用什么来代替?

Unfortunately, it does not give a hint of what to replace it with. So what are we supposed to use instead now?

• Dart SDK 版本:2.12.0-141.0.dev
• Flutter:频道大师，1.25.0-9.0.pre.42

推荐答案

好的找到了，就是如何实例化了:

Ok found it, it's just how to instantiate it:

List<MyClass> _files = [];

编辑:可能是最常见的，根据 文档:

Edit: maybe the most common ones, a bit more detailed according to the docs:

大小为 0 的定长列表

Fixed-length list of size 0

List<MyClass> _list = List<MyClass>.empty();

可增长的列表

List<MyClass> _list = [];
//or
List<MyClass> _list = List<MyClass>.empty(growable: true);

具有预定义填充的固定长度

Fixed length with predefined fill

int length = 3;
String fill = "test";
List<String> _list =  List<String>.filled(length ,fill , growable: true);
// => ["test", "test", "test"]

具有生成功能的列表

int length = 3;
MyClass myFun(int idx) => MyClass(id: idx);
List<MyClass> _list = List.generate(length, myFun, growable: true); 
// => [Instance of 'MyClass', Instance of 'MyClass', Instance of 'MyClass']

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