Design Patterns - Singleton Pattern

using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace DesignPattern_Singleton

{

   class Program

   {

      static void Main(string[] args)

      {

         /* The program will first check if there is an instance of LogManager

         * if there is one, then it will continue to use the instance

         * else it will create a new instance and call the private method 
         * "LogManager"

         * private "LogManager" method will create one text file 
         * with a unique name

         * and "WriteLog" will write the log message to the file 

         * which was created by the LogManager

         */

         LogManager.Instance.WriteLog("SINGLETON PATTERN TEST MESSAGE");

      }

   }

   public class LogManager

   {

      private static LogManager instance;

      private FileStream fileStream;

      private StreamWriter streamWriter;

      public static LogManager Instance

      {

         get

         {

            if (instance == null)

            instance = new LogManager();

            return instance;

         }

      }

      private LogManager()

      {

         string fileName = Environment.CurrentDirectory + "\\ApplicationLog_" + Guid.NewGuid() + ".txt";

         fileStream = File.OpenWrite(fileName);

         streamWriter = new StreamWriter(fileStream);

      }

      public void WriteLog(string logMessage)

      {

         StringBuilder message = new StringBuilder();

         message.AppendLine("Date: " + DateTime.Now.ToString()+" -- Message: "+logMessage);

         streamWriter.WriteLine(message.ToString());

         streamWriter.Flush();

      }

   }

}