英文:
Usage of ArrayList instead of Map in OkHttp
问题
以下是要翻译的内容：
我正在查看 okhttp3 中 Header 类的源代码；为了存储标头和相应的值，使用了一个 ArrayList；因此，对于第一个键 0，其值将在 1 处等等...
这是执行此操作的方法：
final List<String> namesAndValues = new ArrayList<>(20);
Builder addLenient(String name, String value) {
namesAndValues.add(name);
namesAndValues.add(value.trim());
return this;
}
所以我只想知道为什么使用 ArrayList 而不是类似于 Map 的数据结构。
英文:
I was going through the source of the Header class in okhttp3; For storing headers and the corresponding values, an ArrayList is used; So for first key 0, it's value will be at 1 and so on...
This is the method that does this work:
final List<String> namesAndValues = new ArrayList<>(20);
Builder addLenient(String name, String value) {
namesAndValues.add(name);
namesAndValues.add(value.trim());
return this;
}
So I just want to know the reason behind using an ArrayList instead of a Map like data structure
答案1
得分: 4
Header通常以multimap Map<String,List<String>>的形式呈现。
在内部，他们似乎决定使用单个列表来实现相同的目的。最初甚至是一个数组。我会说这更多是开发偏好，因为这是内部代码，对观众而言是隐藏的。
可能的做法是为了节省一些内存，而不是使用multimap并减少垃圾 - 想象一下有10个标头，它将是一个包含10个列表加上其中的项的映射。（通常这些是在每个http请求上创建的）
Headers类还应该有一个方法toMultimap。
英文:
Header usually are presented with multimap Map<String,List<String>>
It seems internally they have decided to use a single list which serves the same purpose. Initially was even an array. I would say it is more a develop preference, as this is internal code and it is hidden for the audience.
Possible could be to save some memory instead of using multimap and less garbage - imagine having 10 headers it will be a map with 10 lists + the items inside.(Usually these are created on every http request)
Headers class should have also a method toMultimap
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