C#中一道關於線程同步的練習題——模擬多窗口售票

題目：模擬窗口賣票，四個窗口同時對外開放售票，需要按順序售出。

要求：輸出每一張票的售出時間和售出窗口，不能出現票未售出或者被售出多次的情況。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.IO;
using System.Reflection;
using System.Diagnostics;

namespace SellTicketsSynchronously
{
    class Program
    {
        //入口
        static void Main(string[] args)
        {
            Ticket tc = new Ticket(10);
            Thread sellWindowA = new Thread(new ParameterizedThreadStart(SellTicket));
            Thread sellWindowB = new Thread(new ParameterizedThreadStart(SellTicket));
            Thread sellWindowC = new Thread(new ParameterizedThreadStart(SellTicket));
            Thread sellWindowD = new Thread(new ParameterizedThreadStart(SellTicket));
            sellWindowA.Name = "Window A";
            sellWindowB.Name = "Window B";
            sellWindowC.Name = "Window C";
            sellWindowD.Name = "Window D";
            sellWindowA.Start(tc);
            sellWindowB.Start(tc);
            sellWindowC.Start(tc);
            sellWindowD.Start(tc);
            sellWindowA.Join();
            sellWindowB.Join();
            sellWindowC.Join();
            sellWindowD.Join();
            Console.WriteLine("Tickets has been sold out. Press any key to quit:");
            Console.ReadLine();
        }
        //賣票方法
        public static void SellTicket(object obj) 
        {
            Ticket ticket = obj as Ticket;
            while (ticket.NumOfTickets>0)
            {
                lock (ticket)
                {
                    if (ticket.NumOfTickets > 0)
                    {
                        try
                        {
                            ticket.NumOfTickets--;
                            Console.WriteLine( DateTime.Now.ToString()+":"+Thread.CurrentThread.Name + " sells a ticket, " + ticket.NumOfTickets + " tickets left.");
                        }
                        catch (Exception ex)
                        {
                            WriteLog(ex);
                        }
                    }
                }
                Random random = new Random();
                Thread.Sleep(random.Next(100,500));
            } 
        }
        //打log方法
        private static void WriteLog(Exception ex)
        {
            string logUrl = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + "\\SellTicketslog.txt";
            if (File.Exists(@logUrl))
            {
                using (FileStream fs = new FileStream(logUrl, FileMode.Append))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.Default))
                    {
                        try
                        {
                            sw.Write(ex);
                        }
                        catch (Exception ex1)
                        {
                            WriteLog(ex1);
                        }
                        finally
                        {
                            sw.Close();
                            fs.Close();
                        }
                    }
                }
            }
            else
            {
                using (FileStream fs = new FileStream(logUrl, FileMode.CreateNew))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.Default))
                    {
                        try
                        {
                            sw.Write(ex);
                        }
                        catch (Exception ex1)
                        {
                            WriteLog(ex1);
                        }
                        finally
                        {
                            sw.Close();
                            fs.Close();
                        }
                    }
                }
            }
        }
    }
    //票類
    class Ticket 
    {
        public int NumOfTickets { get; set; }
        public Ticket(int num) 
        {
            this.NumOfTickets = num;
        }
    }
}

運行結果：

不知道這么寫會不會有問題，求指點。

————————修改版——————————

經過園友指點，我改用了Task寫了這段代碼，其間得到了園友的幫助，非常感謝！

修改后的代碼如下（藍色字體為修改的部分）：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.IO;
using System.Reflection;
using System.Diagnostics;

namespace SellTicketsSynchronously
{
    class Program
    {
        //入口
        static void Main(string[] args) { Ticket tc = new Ticket(10); WaitForAllSales(tc); Console.WriteLine("Tickets has been sold out. Press any key to quit:"); Console.ReadLine(); } //售罄方法 private static void WaitForAllSales(Ticket tc) { //創建一個Task類型的泛型list List<Task> tasks = new List<Task>(); for (int i = 1; i <= 4; i++) { //將所有的售票task存入list tasks.Add(Task.Run(() => { SellTicket(string.Format("Window"+i), tc); })); } //等待所有的task都完成 Task.WaitAll(tasks.ToArray()); } //賣票方法
        public static void SellTicket(string windowName, object obj) 
        {
            string nameOfWindow = windowName;
            Ticket ticket = obj as Ticket;
            while (ticket.NumOfTickets > 0)
            {
                lock (ticket)
                {
                    if (ticket.NumOfTickets > 0)
                    {
                        try
                        {
                            ticket.NumOfTickets--;
                            Console.WriteLine(DateTime.Now.ToString() + ":" + nameOfWindow + " sells a ticket, " + ticket.NumOfTickets + " tickets left.");
                        }
                        catch (Exception ex)
                        {
                            WriteLog(ex);
                        }
                    }
                }
                Random random = new Random();
                Thread.Sleep(random.Next(100,500));
            }
        }
        //打log方法
        private static void WriteLog(Exception ex)
        {
            string logUrl = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + "\\SellTicketslog.txt";
            if (File.Exists(@logUrl))
            {
                using (FileStream fs = new FileStream(logUrl, FileMode.Append))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.Default))
                    {
                        try
                        {
                            sw.Write(ex);
                        }
                        catch (Exception ex1)
                        {
                            WriteLog(ex1);
                        }
                        finally
                        {
                            sw.Close();
                            fs.Close();
                        }
                    }
                }
            }
            else
            {
                using (FileStream fs = new FileStream(logUrl, FileMode.CreateNew))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.Default))
                    {
                        try
                        {
                            sw.Write(ex);
                        }
                        catch (Exception ex1)
                        {
                            WriteLog(ex1);
                        }
                        finally
                        {
                            sw.Close();
                            fs.Close();
                        }
                    }
                }
            }
        }
    }
    //票類
    class Ticket 
    {
        public int NumOfTickets { get; set; }
        public Ticket(int num) 
        {
            this.NumOfTickets = num;
        }
    }
}

運行結果：

歡迎大家發散思維，繼續提出寶貴意見！:)

 ------------------------------------------------------------------------------------------------------------

經過一位朋友細心的發現，上面這個程序邏輯是有問題的，一直都是售票窗口5在售票，修改后的代碼如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.IO;
using System.Reflection;
using System.Diagnostics;

namespace SellTicketsSynchronously
{
    class Program
    {
        //入口
        static void Main(string[] args)
        {
            Ticket tc = new Ticket(20);
            WaitForAllSales(tc);       
            Console.ReadLine();
        }
        //售罄方法
        private static void WaitForAllSales(Ticket tc) 
        {
            //創建一個Task類型的泛型list
            List<Task> tasks = new List<Task>();
            System.Random ran = new Random();
            while (tc.NumOfTickets > 0)
            {
                int i = ran.Next(1,6);
                //將所有的售票task存入list
                tasks.Add(Task.Run(() => { SellTicket(string.Format("Window" + i), tc); }));
                Task.WaitAll(tasks.ToArray());
            }
            Console.WriteLine("Tickets has been sold out. Press any key to quit:");
        }
        //賣票方法
        public static void SellTicket(string windowName, object obj) 
        {
            string nameOfWindow = windowName;
            Ticket ticket = obj as Ticket;
            lock (ticket)
            {
                if (ticket.NumOfTickets > 0)
                {
                    try
                    {
                        ticket.NumOfTickets--;
                        Console.WriteLine(DateTime.Now.ToString() + ":" + nameOfWindow + " sells a ticket, " + ticket.NumOfTickets + " tickets left.");
                    }
                    catch (Exception ex)
                    {
                        WriteLog(ex);
                    }
                }
                Random random = new Random();
                Thread.Sleep(random.Next(100,500));
            }
        }
        //打log方法
        private static void WriteLog(Exception ex)
        {
            string logUrl = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + "\\SellTicketslog.txt";
            if (File.Exists(@logUrl))
            {
                using (FileStream fs = new FileStream(logUrl, FileMode.Append))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.Default))
                    {
                        try
                        {
                            sw.Write(ex);
                        }
                        catch (Exception ex1)
                        {
                            WriteLog(ex1);
                        }
                        finally
                        {
                            sw.Close();
                            fs.Close();
                        }
                    }
                }
            }
            else
            {
                using (FileStream fs = new FileStream(logUrl, FileMode.CreateNew))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.Default))
                    {
                        try
                        {
                            sw.Write(ex);
                        }
                        catch (Exception ex1)
                        {
                            WriteLog(ex1);
                        }
                        finally
                        {
                            sw.Close();
                            fs.Close();
                        }
                    }
                }
            }
        }
    }
    //票類
    class Ticket 
    {
        public int NumOfTickets { get; set; }
        public Ticket(int num) 
        {
            this.NumOfTickets = num;
        }
    }
}

本次修改了售罄方法和入口方法（橙色字體），運行結果如下：

歡迎繼續提出意見！謝謝大家~