C# Language Constructors and Finalizers Static constructor
Example
A static constructor is called the first time any member of a type is initialized, a static class member is called or a static method. The static constructor is thread safe. A static constructor is commonly used to:
- Initialize static state, that is state which is shared across different instances of the same class.
- Create a singleton
Example:
class Animal
{
// * A static constructor is executed only once,
// when a class is first accessed.
// * A static constructor cannot have any access modifiers
// * A static constructor cannot have any parameters
static Animal()
{
Console.WriteLine("Animal initialized");
}
// Instance constructor, this is executed every time the class is created
public Animal()
{
Console.WriteLine("Animal created");
}
public static void Yawn()
{
Console.WriteLine("Yawn!");
}
}
var turtle = new Animal();
var giraffe = new Animal();
Output:
Animal initialized
Animal created
Animal created
If the first call is to a static method, the static constructor is invoked without the instance constructor. This is OK, because the static method can't access instance state anyways.
Animal.Yawn();
This will output:
Animal initialized
Yawn!
See also Exceptions in static constructors and Generic Static Constructors .
Singleton example:
public class SessionManager
{
public static SessionManager Instance;
static SessionManager()
{
Instance = new SessionManager();
}
}
