C# 인터페이스

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace ConsoleApplication1
{
    interface ILogger
    {
        void WriteLog(string message);
    }

    class ConsoleLogger : ILogger
    {
        public void WriteLog(string message)
        {
            Console.WriteLine("{0} {1}", DateTime.Now.ToLocalTime(), message);
        }
    }

    class FileLogger : ILogger
    {
        private StreamWriter writer;

        public FileLogger(string path)
        {
            writer = File.CreateText(path);
            writer.AutoFlush = true;
        }

        public void WriteLog(string message)
        {
            writer.WriteLine("{0} {1}", DateTime.Now.ToShortTimeString(), message);
        }

        class ClimateMonitor
        {
            private ILogger logger;
            public ClimateMonitor(ILogger logger)
            {
                this.logger = logger;
            }

            public void start()
            {
                while (true)
                {
                    Console.Write("온도를 입력해주세요.:");
                    string temperature = Console.ReadLine();
                    if (temperature == "")
                        break;

                    logger.WriteLog("현재온도 : " + temperature);
                }
            }
        }

        class Program
        {
            static void Main(string[] args)
            {
                ClimateMonitor monitor = new ClimateMonitor(new FileLogger("MyLog.txt"));
                monitor.start();
            }
        }
    }
}