Singleton in Java

   // Singleton design pattern in Java
   public class Singleton
   {
       // The private instance of the singleton class:
       private static Singleton instance;

       // Private data associated with the singleton:
       bool logEnabled;

       // Private constructor:
       private Singleton()
       {
           logEnabled = true;
       }

       // Private instance getter:
       private static Singleton GetInstance()
       {
           if(instance == null)
           {
               instance = new Singleton();
           }
           return instance;
       }

       // Public static methods for accessing the singleton class:

       // For this example, we'll use it as a logging service:
       public static void EnableLogging(bool state)
       {
           // Get the instance via the static method:
           Singleton logger = Singleton.GetInstance();
           // Set the instance state:
           logger.logEnabled = state;
       }

       public static void LogMessage(string message)
       {
           // Get the instance via the static method:
           Singleton logger = Singleton.GetInstance();
           // Check the instance's logging state:
           if(logger.logEnabled)
           {
               // Write to the console window:
               System.out.println(message);
           }
       }
   }