问题描述
如何在静态类中声明静态字典对象？我试过
How to declare a static dictionary object inside a static class? I tried
public static class ErrorCode
{
public const IDictionary<string, string> ErrorCodeDic = new Dictionary<string, string>()
{
{ "1", "User name or password problem" }
};
}
但编译器抱怨说引用类型的const字段除了字符串之外，只能用null 来初始化。
But the compiler complains that "A const field of a reference type other than string can only be initialized with null".
推荐答案
如果您要声明一次字典，永远不要更改，然后将其声明为只读方式：
If you want to declare the dictionary once and never change it then declare it as readonly:
private static readonly Dictionary<string, string> ErrorCodes
= new Dictionary<string, string>
{
{ "1", "Error One" },
{ "2", "Error Two" }
};
如果要将字典项目只读（不仅仅是引用，也是集合中的项目） ）然后您将不得不创建一个实现IDictionary的只读字典类。
If you want to dictionary items to be readonly (not just the reference but also the items in the collection) then you will have to create a readonly dictionary class that implements IDictionary.
查看ReadOnlyCollection作为参考。
Check out ReadOnlyCollection for reference.
BTW const只能在内联声明标量值时使用。
BTW const can only be used when declaring scalar values inline.
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