任务的返回类型错误

Question

怎么了 以及如何解决？我正在尝试学习c＃-task中的新主题。当我运行时，我收到错误消息： Error CS0407 'Task MainWindow.btn1_ClickAsync(object, RoutedEventArgs)' has the wrong return type

 public async Task btn1_ClickAsync(object sender, RoutedEventArgs e)
            {
                txtState.Text = "btn1_Click started";
               await LongRunningFunc1();
                txtState.Text = "btn1_Click finished";

            }

        private async Task LongRunningFunc1()
        {
            txt1.Text = "Processing 1 .....";
            btn1.Content = "Wait";
            await Task.Delay(5000);
            txt1.Text = "Hello From Func1";
            btn1.Content = "Click";
        }

WPF设计师：

<Grid>
        <TextBlock Name="txtState" Margin="265,10,274,356"/>
        <TextBlock Name="txt1" Height="50" RenderTransformOrigin="0.966,-0.95" Margin="281,68,320,301"/>
        <TextBlock Name="txt2" Height="50" Margin="253,238,274,131" />
        <Button Name="btn1" Background="Red" Margin="281,127,300,208" Click="btn1_ClickAsync"></Button>
        <Button Name="btn2" Background="Aqua" Margin="298,309,311,27"></Button>
    </Grid>

Answer 1

事件处理程序必须是async void方法：

public async void btn1_ClickAsync(object sender, RoutedEventArgs e)

Answer 2

按钮单击事件async void是可接受的少数方法签名之一。更改方法以阅读

public async void btn1_ClickAsync(object sender, RoutedEventArgs e)

你应该没事的

Answer 3

因为它是一个事件处理程序，所以应该是async void

public async void btn1_ClickAsync(object sender, RoutedEventArgs e)

请注意，这async void是一种特殊情况，通常应避免。请参阅async/await - 何时返回任务 vs void？了解详情。