使用Winforms和C#更新继续的文本框

Question

C#noob来自其他语言的经验.(最值得注意的是Java).

我正在看这个问题的代码.这是VS 2013中的标准WinForms C#项目:

在表单上放一个按钮和一个文本框,然后使用以下代码:

private void button1_Click(object sender, EventArgs e)
{
    Task.Factory.StartNew<int>(() => DelayedAdd(5, 10))
        .ContinueWith(t => DelayedAdd(t.Result, 20))
        .ContinueWith(t => DelayedAdd(t.Result, 30))
        .ContinueWith(t => DelayedAdd(t.Result, 50))
        .ContinueWith(t => textBox1.Text = t.Result.ToString(),
            TaskScheduler.FromCurrentSynchronizationContext());
}

private int DelayedAdd(int a, int b)
{
    Thread.Sleep(500);
    return a + b;
}

按下按钮,等待2秒钟DelayedAdd以完成四个呼叫,并在文本框中显示结果(115). 每次DelayedAdd通话后如何才能在结果文本框中显示结果？

我试图推动每次通话之间的最后延续,

Task.Factory.StartNew<int>(() => DelayedAdd(5, 10))
    .ContinueWith(t => textBox1.Text = t.Result.ToString(),
        TaskScheduler.FromCurrentSynchronizationContext())

    .ContinueWith(t => DelayedAdd(t.Result, 20))
    .ContinueWith(t => textBox1.Text = t.Result.ToString(),
        TaskScheduler.FromCurrentSynchronizationContext())

    .ContinueWith(t => DelayedAdd(t.Result, 30))
    .ContinueWith(t => textBox1.Text = t.Result.ToString(),
        TaskScheduler.FromCurrentSynchronizationContext())

    .ContinueWith(t => DelayedAdd(t.Result, 50))
    .ContinueWith(t => textBox1.Text = t.Result.ToString(),
        TaskScheduler.FromCurrentSynchronizationContext());

但是失败了,我猜是因为我插入的延续不会返回整数结果t.我是一个C#noob,我甚至不知道如何解决这个问题,更不用说以惯用的方式做到这一点.

Answer 1

我只是改变DelayedAdd方法:

    private void button1_Click(object sender, EventArgs e)
    {
        Task.Factory.StartNew<int>(() => DelayedAdd(5, 10))
            .ContinueWith(t => DelayedAdd(t.Result, 20))
            .ContinueWith(t => DelayedAdd(t.Result, 30))
            .ContinueWith(t => DelayedAdd(t.Result, 50));
    }

    private int DelayedAdd(int a, int b)
    {
        if (textBox1.InvokeRequired)
        {
            textBox1.BeginInvoke((Action)(() => textBox1.Text = (a + b).ToString()));
        }
        Thread.Sleep(500);
        return a + b;
    }

Answer 2

知道了！如果有人有更好/更有趣的选择，请回答。

首先，我尝试使用多行 lambda 来代替我的问题中的错误延续：

    .ContinueWith(t => {
        textBox1.Text = t.Result.ToString();
        return t.Result;
    },
        TaskScheduler.FromCurrentSynchronizationContext()); 
    }

这有点冗长和重复，所以我把它干掉了：

    private void button1_Click(object sender, EventArgs e)
    {
        // SCHEDULING LOGIC
        Task.Factory.StartNew<int>(() => DelayedAdd(5, 10))
            .ContinueWith(t => UpdateText(t.Result),
                TaskScheduler.FromCurrentSynchronizationContext())

            .ContinueWith(t => DelayedAdd(t.Result, 20))
            .ContinueWith(t => UpdateText(t.Result),
                TaskScheduler.FromCurrentSynchronizationContext())

            .ContinueWith(t => DelayedAdd(t.Result, 30))
            .ContinueWith(t => UpdateText(t.Result),
                TaskScheduler.FromCurrentSynchronizationContext())

            .ContinueWith(t => DelayedAdd(t.Result, 50))
            .ContinueWith(t => UpdateText(t.Result),
                TaskScheduler.FromCurrentSynchronizationContext()); 
    }

    private int UpdateText(int i)
    {
        // UI LOGIC
        textBox1.Text = i.ToString();
        return i;
    }

    private int DelayedAdd(int a, int b)
    {
        // PROCESS LOGIC
        Thread.Sleep(500);
        return a + b;
    }