c# - ArgumentException 的正确用法？

Question

据我所知，ArgumentExceptions 通常是这样使用的:

public void UpdateUser(User user)
{
    if (user == null) throw new ArgumentException("user");
    // etc...
}

但是如果我有这样的东西怎么办:

public void UpdateUser(int idOfUser)
{
    var user = GetUserById(idOfUser);
    if (user == null) throw new ArgumentException("idOfUser");
    // etc...
}

那还是 ArgumentException 吗？

Answer 1

第一个

if (user == null) throw new ArgumentException("user");

应该是

if (user == null) throw new ArgumentNullException("user");

如果可能你不应该抛出 ArgumentException直接

The primary derived classes of ArgumentException are ArgumentNullException and ArgumentOutOfRangeException. These derived classes should be used instead of ArgumentException, except in situations where neither of the derived classes is acceptable.

第二个例子，这里Should I throw a KeyNotFoundException for a database lookup?他们建议(在评论中)

if (user == null) throw new ObjectNotFoundException();

它在 System.Data 中定义:System.Data.ObjectNotFoundException .