C#, cannot understand this error?
- by 5YrsLaterDBA
I am using VS2008. I have a project, SystemSoftware project, connect with a database and we are using L2E. I have a RuntimeInfo class which contains some shared information there. It looks like this:
public class RuntimeInfo
{
public const int PWD_ExpireDays = 30;
private static RuntimeInfo thisObj = new RuntimeInfo();
public static string AndeDBConnStr = ConfigurationManager.ConnectionStrings["AndeDBEntities"].ConnectionString;
private RuntimeInfo() {
}
/// <summary>
///
/// </summary>
/// <returns>Return this singleton object</returns>
public static RuntimeInfo getRuntimeInfo()
{
return thisObj;
}
}
Now I added a helper project, AndeDataViewer, to the solution which creates a simple UI to display data from the database for testing/verification purpose.
I don't want to create another set of Entity Data Model in the helper project. I just added all related files as a link in the new helper project.
In the AndeDataViewer project, I get the connection string from above RuntimeInfo class which is a class from my SystemSoftware project as a linked file. The code in AndeDataViewer is like this:
public class DbAccess : IDisposable
{
private String connStr = String.Empty;
public DbAccess()
{
connStr = RuntimeInfo.AndeDBConnStr;
}
}
My SystemSoftware works fine that means the RuntimeInfo class has no problem there. But when I run my AndeDataViewer, the statement inside above constructor,
connStr = RuntimeInfo.AndeDBConnStr;
, throws an exception. The exception is copied here:
System.TypeInitializationException was unhandled
Message="The type initializer for 'MyCompany.SystemSoftware.SystemInfo.RuntimeInfo' threw an exception."
Source="AndeDataViewer"
TypeName="MyCompany.SystemSoftware.SystemInfo.RuntimeInfo"
StackTrace:
at AndeDataViewer.DbAccess..ctor() in C:\workspace\SystemSoftware\Other\AndeDataViewer\AndeDataViewer\DbAccess.cs:line 17
at AndeDataViewer.Window1.rbRawData_Checked(Object sender, RoutedEventArgs e) in C:\workspace\SystemSoftware\Other\AndeDataViewer\AndeDataViewer\Window1.xaml.cs:line 69
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
....
InnerException: System.NullReferenceException
Message="Object reference not set to an instance of an object."
Source="AndeDataViewer"
StackTrace:
at MyCompany.SystemSoftware.SystemInfo.RuntimeInfo..cctor() in C:\workspace\SystemSoftware\SystemSoftware\src\systeminfo\RuntimeInfo.cs:line 24
InnerException:
I cannot understand this because it looks fine to me but why there is an exception? we cannot access static variable when a class is a linked class? A linked class should be the same as the local class I think. "Linked" here means when I add file I use "Add As Link".
