c# - NavigationService.Navigate 错误

Question

我是 C# 编程的新手，我的代码有问题。我创建了一个按钮并在其上应用了一个事件点击，它通过 NavigationService 技术打开了我项目的另一个页面。

这是脚本:

private void click_login(object sender, RoutedEventArgs e)
{
    NavigationService nav = NavigationService.GetNavigationService(this); 
    nav.Navigate(new Uri("Window1.xaml", UriKind.RelativeOrAbsolute));
}

当我执行时，我得到这个错误:

The object reference is not set to an instance of an object with an InnerException null.

你能帮帮我吗？

Answer 1

您的 nav 对象为 null，因为您正在尝试获取 WPF 窗口的 NavigationService。

但对于导航，您需要 Page ( Navigation Overview on MSDN )

一个小例子:

创建到Page的Page1.xaml、Page2.xaml

在 App.xaml 中更改StartupUri 到 StartupUri="Page1.xaml"

Page1 Xaml:

 <StackPanel>
     <TextBlock Text="Hello from  Page1" />
     <Button Click="Button_Click" Content="Navigate to page 2"></Button>
 </StackPanel>

Page1 cs:

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        NavigationService nav = NavigationService.GetNavigationService(this);
        nav.Navigate(new Uri("Page2.xaml", UriKind.RelativeOrAbsolute));
    }

Page2 Xaml:

 <StackPanel>
     <TextBlock Text="Hello from  Page2" />
     <Button Click="Button_Click" Content="Navigate to page 1"></Button>
 </StackPanel>

Page2 cs:

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        NavigationService nav = NavigationService.GetNavigationService(this);
        nav.Navigate(new Uri("Page1.xaml", UriKind.RelativeOrAbsolute));
    }