Thread-safe Singleton Pattern Example in C#

 

The Singleton pattern is used when you need one, and only one instance of your class. Sometimes you see this pattern used in cases where the construction of a class is expensive (like a file stream). It can be lazy loaded (at runtime instead of compiletime) and must be thread-safe. The class gets a public method or property named Instance, responsible for creating the Singleton. The constructor of the Singleton class is private, so no one can construct a new instance from the class by applying ‘new’.

using System; namespace Singleton { class Program { static void Main(string[] args) { // Lazy loaded object // Singleton gets created on first call Singleton.Instance.SomeProperty = 0; Singleton.Instance.SomeMethod(); } } public class Singleton { // Private constructor to prevent 'new' private Singleton() { } // The instance read only property public static Singleton Instance { get { return Nested.instance; } } // Nested class with the actual Singleton object private class Nested { internal static readonly Singleton instance = new Singleton(); static Nested() { } } // Additional methods and propeties public int SomeProperty { get; set; } public void SomeMethod() { } } }