Why is this an issue?
Nullable value types can hold either a value or null. The value held in the nullable type can be accessed with the Value
property or by casting it to the underlying type. Still, both operations throw an InvalidOperationException when the value is
null. A nullable type should always be tested before the value is accessed to avoid the exception.
Noncompliant code example
public void Sample(bool condition)
{
int? nullableValue = condition ? 42 : null;
Console.WriteLine(nullableValue.Value); // Noncompliant
int? nullableCast = condition ? 42 : null;
Console.WriteLine((int)nullableCast); // Noncompliant
}
Compliant solution
public void Sample(bool condition)
{
int? nullableValue = condition ? 42 : null;
if (nullableValue.HasValue)
{
Console.WriteLine(nullableValue.Value);
}
int? nullableCast = condition ? 42 : null;
if (nullableCast is not null)
{
Console.WriteLine((int)nullableCast);
}
}
Resources
