Question

我正在测试一些东西但是......我陷入了困境。我测试了许多东西，看着网络，但没有。在MainPage.xaml中：

    <SplitView.Content>
        <Frame Name="MainPageMyFrame"></Frame>
    </SplitView.Content>

在MainPage的.cs中：

    private void ListView_ItemClick(object sender, ItemClickEventArgs e)
    {
        if (MainPageListView.SelectedIndex == 0)
        {
            MainPageMyFrame.Navigate(typeof(Pages.MainWindow));
        }
    }

每次我点击项目ID 0;即时通讯，当它想要导航时：

Exception thrown: 'System.NullReferenceException'

MainWindow是UserControl。有谁知道如何解决这个错误？

@Update MainPage.xaml中

    <SplitView Grid.Row="1" Name="MainPageSplitView" OpenPaneLength="200" CompactPaneLength="50" DisplayMode="CompactOverlay">
        <SplitView.Pane>
            <ListView Name="MainPageListView" Background="LightGray" ItemClick="ListView_ItemClick" IsItemClickEnabled="True">
                <ListView.Items>

                    <ListViewItem BorderThickness="0,1,0,1" BorderBrush="DarkGray">
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Foreground="Black" FontFamily="Segoe MDL2 Assets" Text="&#xE806;" FontSize="25" />
                            <TextBlock Margin="15, 0" Foreground="Black" FontSize="20" VerticalAlignment="Center" Text="Rozkład jazdy" />
                        </StackPanel>
                    </ListViewItem>

                    <ListViewItem BorderThickness="0,0,0,1" BorderBrush="DarkGray">
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Foreground="Black" FontFamily="Segoe MDL2 Assets" Text="&#xEC15;" FontSize="25" />
                            <TextBlock Margin="15, 0" Foreground="Black" FontSize="20" VerticalAlignment="Center" Text="Komunikaty" />
                        </StackPanel>
                    </ListViewItem>

                </ListView.Items>
            </ListView>
        </SplitView.Pane>
        <SplitView.Content>
            <Frame Name="MainPageMyFrame" />
        </SplitView.Content>
    </SplitView>

我们走了，它的.cs：

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();

        MainPageListView.SelectedIndex = 0;
    }

    private void MainPageRelativePanelButton_Click(object sender, RoutedEventArgs e)
    {
        MainPageSplitView.IsPaneOpen = !MainPageSplitView.IsPaneOpen;
    }

    private void ListView_ItemClick(object sender, ItemClickEventArgs e)
    {
        if((sender as ListView).SelectedIndex  == 0) // rozklad jazdy
        {
            MainPageMyFrame.Navigate(typeof(Pages.MainWindow)); // from here i want to navigate
        }
    }
}

MainWindow.xaml（我要导航的页面）

<UserControl
    x:Class="RozkladJazdy.Pages.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:RozkladJazdy.Pages"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300"
    d:DesignWidth="400">

    <Grid>
        <StackPanel Name="MainPageStackPanel" VerticalAlignment="Center" HorizontalAlignment="Center">

            <TextBlock VerticalAlignment="Center" Name="MainPageTextBlock"/>
            <ProgressRing Name="MainPageProgressRing" IsActive="True" Width="50" Height="50"/>

        </StackPanel>
    </Grid>
</UserControl>

.cs：

using RozkladJazdy.Model;
using Windows.UI;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media;

// The User Control item template is documented at http://go.microsoft.com/fwlink/?LinkId=234236

namespace RozkladJazdy.Pages
{
    public sealed partial class MainWindow : UserControl
    {
        public static string[,] Lines;

        public MainWindow()
        {
            this.InitializeComponent(); // here the error is thrown
        }
    }
}

就是这样，这里有什么问题吗？

Answer 1

@Anthony Russell和@SWilko说，问题是我想导航到UserControl，我应该导航到一个页面。

在我创建WPF应用程序之前，所以我忘记了在UWP中它应该是一个页面。

UWP帧空引用

1 个答案: