Question

In .NET 4.0, if I have the following code:

....
T instantiatedClass;
try
{
    instantiatedClass = (T)assembly.CreateInstance(classFullName);
}
catch (Exception ex)
{
    errMsg = string.Format("Error creating an instance of type \"{0}\".", classes.First().FullName);
    throw new ApplicationException(errMsg, ex);
}

Assuming that classFullName is a correct type in the assembly, and that the type “T” implements a public interface, is there any circumstance where 1) No exception would be thrown, and 2) instantiatedClass would be null?

Thanks for any help.

Answer 1

If there is no default constructor or the assumption that classFullName is valid in the assembly is incorrect or anything prevents the CreateInstance call from calling a constructor an exception is thrown.

So the only way that this could fail for you is if the called constructor returns a null value. But this can’t happen since if no exception is raised during construction, then the constructor call will return a reference to the new object, and if an exception is raised you catch it.