为什么打印消息不会在我的C＃代码中打印？

Question

我正在尝试在循环运行之前将消息“ printing ...”打印到txtMessage.Text文本框中，但是在循环运行之前它永远不会打印到文本框中。 知道为什么吗？

else
            {
                txtMessage.Text = "Printing...";
                for (int i = numberCopies; i != 0; i--)
                {
                    int paper = Convert.ToInt32(lblPaperAmount.Text);
                    paper--;
                    if (paper == 480 || paper == 380 || paper == 400 || paper == 200)
                    {
                        MessageBox.Show("There is a paper Jam! Please remove the Jam and then hit the ok button to continue!", "Important Message", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);

                    }
                    lblPaperAmount.Text = Convert.ToString(Convert.ToInt32(lblPaperAmount.Text) - 1);
                    lblTonerAmount.Text = Convert.ToString(Convert.ToInt32(lblTonerAmount.Text) - 1);
                    Thread.Sleep(1000);
                }
                txtMessage.Text = "Job is completed!";
            }

Answer 1

设置文本后，尝试将呼叫添加到“刷新”。 您可能足够快地进入循环，直到退出后刷新才会发生。

else
{
    txtMessage.Text = "Printing...";
    txtMessage.Refresh(); //force the control to redraw
    for (int i = numberCopies; i != 0; i--)
    {
        int paper = Convert.ToInt32(lblPaperAmount.Text);
        paper--;
        if (paper == 480 || paper == 380 || paper == 400 || paper == 200)
        {
            MessageBox.Show("There is a paper Jam! Please remove the Jam and then hit the ok button to continue!", "Important Message", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);

        }
        lblPaperAmount.Text = Convert.ToString(Convert.ToInt32(lblPaperAmount.Text) - 1);
        lblTonerAmount.Text = Convert.ToString(Convert.ToInt32(lblTonerAmount.Text) - 1);
        Thread.Sleep(1000);
    }
    txtMessage.Text = "Job is completed!";
}

Answer 2

您的代码在单个线程中运行。 您应该将文本设置为“正在打印...”，然后断开一个新线程以使卡纸循环。

请参阅此问题和前3个答案。