[英]The type initializer for '' threw an exception
考虑以下代码:
public class CountEnum : EnumDataType
{
public static readonly CountEnum CANADA = new CountEnum("CA", "Canada");
public static readonly CountEnum DEFAULT = new CountEnum();
private static readonly EnumDataTypeList OPTIONS = new EnumDataTypeList();
public static readonly CountEnum UNITED_STATES = new CountEnum("US", "United States");
public static readonly CountEnum UNSET = new CountEnum();
private CountEnum()
{
}
private CountEnum(string code, string name)
{
base.code = code;
base.name = name;
OPTIONS.Add(this); // This is the line 23
}
以下是例外情况:
System.TypeInitializationException was caught
Message=The type initializer for 'CP.BusinessLogic.VConfig' threw an exception.
Source=CP.BusinessLogic
TypeName=CP.BusinessLogic.VConfig
StackTrace:
at CP.BusinessLogic.VConfig.get_Instance()
at CP.Fac.CPFac.GetActs() in C:\tfs_src\TeamProject\Main\Source\DApp\CPApp\Fac\CPFac.cs:line 170
InnerException: System.TypeInitializationException
Message=The type initializer for 'CP.Types.CountEnum' threw an exception.
Source=CP.BusinessLogic
TypeName=CP.Types.CountEnum
StackTrace:
at CP.BusinessLogic.VConfig..ctor() in C:\tfs_src\TeamProject\Main\Source\DApp\CPApp\BusinessLogic\VConfig.cs:line 14
at CP.BusinessLogic.VConfig..cctor() in C:\tfs_src\TeamProject\Main\Source\DApp\CPApp\BusinessLogic\VConfig.cs:line 11
InnerException: System.NullReferenceException
Message=Object reference not set to an instance of an object.
Source=CP.DataObject
StackTrace:
at CP.Types.CountEnum..ctor(String code, String name) in C:\tfs_src\TeamProject\Main\Source\DApp\CPApp\Types\CountEnum.cs:line 23
at CP.Types.CountEnum..cctor() in C:\tfs_src\TeamProject\Main\Source\DApp\CPApp\Types\CountEnum.cs:line 8
InnerException:
我无法弄清楚为什么我在运行时得到这个异常。 我没有得到任何构建错误,代码看起来正确。
根据您的堆栈跟踪判断,我认为您错过了有罪的代码。 例如,也许它实际上是这样的:
public class CountEnum
{
public static readonly CountEnum DEFAULT = new CountEnum();
private static readonly List<CountEnum> AllInstances = new List<CountEnum>();
private CountEnum()
{
AllInstances.Add(this);
}
}
这将表示堆栈跟踪显示的方式, CountEnum
构造函数抛出NullReferenceException
。 但是,我们无法确定,因为您没有包含CountEnum
构造函数的主体(或者根本没有为CountEnum
发布有效代码)。
从根本上说,这是你应该看到的堆栈跟踪的一点:
InnerException: System.NullReferenceException
Message=Object reference not set to an instance of an object.
Source=CP.DataObject
StackTrace:
at CP.Types.CountEnum..ctor(String code, String name) in C:\...\CountEnum.cs:line 23
at CP.Types.CountEnum..cctor() in C:\...\CountEnum.cs:line 8
您应该查看CountEnum.cs
第23 CountEnum.cs
- 这就是抛出异常的原因。
编辑:好的,现在我们可以看到有问题的代码,它与我的猜测非常相似。 看看这段代码:
public static readonly CountEnum CANADA = new CountEnum("CA", "Canada");
public static readonly CountEnum DEFAULT = new CountEnum();
private static readonly EnumDataTypeList OPTIONS = new EnumDataTypeList();
这些变量将按照您指定的顺序进行初始化 - 因此,对于CountEnum("CA", "Canada")
调用将在OPTIONS
具有非空值之前执行...当您尝试将其添加到OPTIONS
,你会以完全正常的方式得到一个例外。
你可以通过将OPTIONS
的声明移到顶部来解决这个问题:
private static readonly EnumDataTypeList OPTIONS = new EnumDataTypeList();
public static readonly CountEnum CANADA = new CountEnum("CA", "Canada");
public static readonly CountEnum DEFAULT = new CountEnum();
这保证可行,但它是一个相当脆弱的设计。 我过去曾经使用过这样的设计,但是当你需要特定的初始化命令时,你可能会陷入困境。
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