Question

MainWindow.xaml

<CheckBox Content="Enable" Height="16" HorizontalAlignment="Left" Margin="190,40,0,0" Name="checkBox_Enable" VerticalAlignment="Top" IsChecked="True" Unchecked="checkBox_Enable_Unchecked" Checked="checkBox_Enable_Checked" />
    <Label Content="Fullscreen:" Height="15" HorizontalAlignment="Left" Margin="227,63,0,0" Name="label3" VerticalAlignment="Top" Width="56" Padding="1" />
    <TextBox HorizontalAlignment="Right" Margin="0,86,243,0" Name="textBox_Hotkey_Fullscreen" Width="33" Height="18" VerticalAlignment="Top" />
    <Label Content="Custom field:" HorizontalAlignment="Left" Margin="227,110,0,136" Name="label5" Padding="1" />
    <TextBox Height="18" HorizontalAlignment="Left" Margin="227,131,0,0" Name="textBox_Hotkey_Customfield" VerticalAlignment="Top" Width="33" />
    <Label Content="Window-related:" HorizontalAlignment="Left" Margin="227,155,0,87" Name="label4" Padding="1" />
    <TextBox HorizontalAlignment="Left" Margin="227,0,0,112" Name="textBox_Hotkey_Windowrelated" Width="33" Height="18" VerticalAlignment="Bottom"  />

MainWindow.xaml.cs

    private void checkBox_Enable_Unchecked(object sender, RoutedEventArgs e)
    {
        textBox_Hotkey_Fullscreen.IsEnabled = false;
        textBox_Hotkey_Customfield.IsEnabled = false;
        textBox_Hotkey_Windowrelated.IsEnabled = false;
    }

    //There are no problems after purging this function. However, the controls couldn't be "re-enabled", what obviously makes my concept pointless.  
    private void checkBox_Enable_Checked(object sender, RoutedEventArgs e)
    {

        textBox_Hotkey_Fullscreen.IsEnabled = true; 
        textBox_Hotkey_Customfield.IsEnabled = true;
        textBox_Hotkey_Windowrelated.IsEnabled = true;
    }

为什么它会在启动后抛出NullReferenceException？

Answer 1

我建议使用Binding（从xaml中删除事件处理程序）

 IsEnabled="{Binding ElementName=checkBox_Enable, Path=IsChecked}"

对于您要使用复选框启用/禁用的每个控件。

Answer 2

为什么它会在启动后抛出NullReferenceException？

因为当CheckBox触发事件时，并非所有控件都已加载。

我建议binding将CheckBox添加到bool并将其他控件'IsEnabled绑定到该（directly绑定到CheckBox）。

使用单个复选框动态禁用一堆文本框

2 个答案: