Singleton Pattern Code Review

Code Download

Download Description:singleton pattern download
.NET Framework:3.5
.NET Language:C#
Date Published:2009-07-01
Download Size:8 KB

Define the Singleton Object

Define the Singleton class with the required getInstance() method used to create a single instance of the class (object).

class Singleton { private static Singleton instance = null; private static Object syncLock = new Object();
public String Item { get; set; }
private Singleton() {}
public static Singleton getInstance() { if (instance == null) { lock (syncLock) { if (instance == null) { Console.WriteLine("****** Creating Singleton instance ******"); instance = new Singleton(); } } } return instance; } }

Use the Singleton Pattern

The Program class creates two instances of the Singleton class (object) and compares these instances to prove they are identical and that only one version of the class (object) exists.

class Program { static void Main(string[] args) { Console.WriteLine("Getting singleton 1."); Singleton instance1 = Singleton.getInstance(); instance1.Item = "Hello World!"; Console.WriteLine(String.Format("Got singleton 1 {0}.", instance1));
Console.WriteLine("\nGetting singleton 2."); Singleton instance2 = Singleton.getInstance(); instance2.Item = "Foo"; Console.WriteLine(String.Format("Got singleton 2 {0}.", instance1));
if (instance1 == instance2) { Console.WriteLine("\nInstance 1 and Instance 2 are equal"); } Console.WriteLine(String.Format("Instance 1, Item = {0}.", instance1.Item)); Console.WriteLine(String.Format("Instance 2, Item = {0}.", instance2.Item));
Console.Read(); } }