線程處理時的 C# InvalidOperationException

Question

我試圖讓一個函數每 200 毫秒運行一次，以便它可以顯示程序首次啟動和現在之間的時間差。 我嘗試使用以下代碼進行線程化：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Timers;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace ComputerTimer
{
    public partial class MainWindow : Window
    {
        private DateTime startTime, endTime;
        private static System.Timers.Timer timer1;
        private bool running = true;

        public MainWindow()
        {
            InitializeComponent();

            startTime = DateTime.Now;

            //makes new timer with 200 milliseconds interval
            timer1 = new System.Timers.Timer(200);
            timer1.Elapsed += new ElapsedEventHandler(timer1_Tick);
            timer1.Interval = 200;
            timer1.Enabled = true;

        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            while (running)
            {
                endTime = DateTime.Now;
                TimeSpan span = endTime - startTime; //gets difference between now and when the program was started
                Title.Content = span.ToString().Substring(0, 8); //gets first 8 characters (taking out milliseconds)
            }
        }

        private void btnStop_Click(object sender, RoutedEventArgs e)
        {
            //when button is pressed to stop timer
            running = false;
        }
    }
}

但這只是拋出異常'InvalidOperationException'並說“附加信息：調用線程無法訪問此對象，因為不同的線程擁有它。” 關於第 48 行

Title.Content = span.ToString().Substring(0, 8); //gets first 8 characters (taking out milliseconds)

我很困惑從這里做什么，並在整個堆棧溢出中搜索以尋找答案，但似乎沒有任何效果。 我也嘗試過 DispatcherTimer 但沒有運氣。

編輯：這是對我有用的答案，適用於將來查看此問題的任何人

namespace ComputerTimer
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private DateTime startTime, endTime;
        private DispatcherTimer dtClockTime;

        public MainWindow()
        {
            InitializeComponent();

            startTime = DateTime.Now;

            dtClockTime = new DispatcherTimer();

            dtClockTime.Interval = new TimeSpan(0, 0, 0, 0, 200); //in days, Hour, Minutes, Seconds, millis
            dtClockTime.Tick += dtClockTime_Tick;

            dtClockTime.Start();

        }

        private void dtClockTime_Tick(object sender, EventArgs e)
        {
            endTime = DateTime.Now;
            TimeSpan span = endTime - startTime; //gets difference between now and when the program was started
            Title.Content = span.ToString().Substring(0, 8);
        }

        private void btnStop_Click(object sender, RoutedEventArgs e)
        {
            //when button is pressed to stop timer
            dtClockTime.Stop();
        }
    }
}

Answer 1

您已經在計時器Tick事件中創建了一個無限循環，您不應該在其中有一個while(x)循環。

private void timer1_Tick(object sender, EventArgs e)
{
     endTime = DateTime.Now;
     TimeSpan span = endTime - startTime; //gets difference between now and when the program was started
     Title.Content = span.ToString().Substring(0, 8); //gets first 8 characters (taking out milliseconds)
 }

你的停止按鈕應該只是禁用計時器

private void btnStop_Click(object sender, RoutedEventArgs e)
{
     timer1.Enabled = false;
}

---

編輯：可能是您需要設置計時器的SynchronisingObject

timer1.SynchronisingObject = this;

---

如果上述情況失敗，對於 wpf 應用程序（對不起，我最初錯過了wpf標簽），您應該使用DispatcherTimer代替System.Timers.Timer 。

設置與您現有的代碼大致相同，它只是使用不同類型的計時器，它在正確的（UI）線程上引發滴答事件。

---

順便說一句，不需要對DateTime對象進行字符串混搭，有一些方法可以格式化時間跨度

Title.Content = span.ToString("mm:ss.ffff");

Answer 2

僅為您的計時器添加 SynchronisingObject 參數。

像這樣：

timer1.SynchronisingObject = this;