sealed class SingletonClass
{
// Static members are lazily initialized.
// .NET guarantees thread safety for static initialization
private static readonly SingletonClass instance =
new SingletonClass();

// Note: constructor is private.
private SingletonClass(){}

public static SingletonClass GetInstance()
{
return instance;
}
}
منبع : http://www.dofactory.com/Patterns/PatternSingleton.aspx