為什么打印消息不會在我的C＃代碼中打印？

Question

我正在嘗試在循環運行之前將消息“ printing ...”打印到txtMessage.Text文本框中，但是在循環運行之前它永遠不會打印到文本框中。 知道為什么嗎？

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

設置文本后，嘗試將呼叫添加到“刷新”。 您可能足夠快地進入循環，直到退出后刷新才會發生。

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

您的代碼在單個線程中運行。 您應該將文本設置為“正在打印...”，然后斷開一個新線程以使卡紙循環。

請參閱此問題和前3個答案。