我正在尝试创建一个新的Time表应用，用户输入rowNo和colNo。 到目前为止，我已经完成了这段代码，但每当我尝试从数组中检索文本框时，我都会得到一个Null引用异常。
XAML
<ScrollViewer HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible" Background="{x:Null}">
<Grid Name="bigGrid" Height="780" Width="1300">
<Grid.Background>
<ImageBrush Stretch="Fill" ImageSource="/TimeTableBackground.jpg"/>
</Grid.Background>
<StackPanel Name="panel" Height="128" Margin="0,-3,0,0" VerticalAlignment="Top" Background="#1D000000">
<TextBlock TextWrapping="Wrap" Text="Time Table" FontSize="24" FontStyle="Italic" FontFamily="Segoe WP" FontWeight="Bold" Foreground="#FFC83DA2"/>
<TextBlock TextWrapping="Wrap" Text="Edit Table" Height="72" Padding="0" FontSize="64" FontFamily="Comic Sans MS" FontStyle="Italic" Foreground="#FFFF6BD7"/>
</StackPanel>
<Grid Name="grid1" HorizontalAlignment="Stretch" Height="{Binding ElementName=LayoutRoot,Path=ActualHeight}" Width="5000" VerticalAlignment="Bottom" Background="#1C000000" Margin="-14,0,14,19" ShowGridLines="True" />
</Grid>
</ScrollViewer>
<!--Sample code showing usage of ApplicationBar-->
<phone:PhoneApplicationPage.ApplicationBar>
<shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
<shell:ApplicationBarIconButton IconUri="/Images/appbar.edit.rest.png" Text="Button 1" Click="ApplicationBarIconButton_Click"/>
<shell:ApplicationBarIconButton IconUri="/Images/appbar.save.rest.png" Text="Button 2"/>
<shell:ApplicationBar.MenuItems>
<shell:ApplicationBarMenuItem Text="MenuItem 1"/>
<shell:ApplicationBarMenuItem Text="MenuItem 2"/>
</shell:ApplicationBar.MenuItems>
</shell:ApplicationBar>
XAML只是知道控件的名称。但是，C＃代码就是其中之一。
C＃
public partial class Edit_page : PhoneApplicationPage
{
private TextBox[,] tbArray = new TextBox[9,9];
int rowNo = 6, colNo = 6;
public Edit_page()
{
InitializeComponent();
//for loops to add rows and columns to the main grid
for (int j = 0; j <= rowNo; j++)
{
RowDefinition Row = new RowDefinition();
grid1.RowDefinitions.Add(Row);
Row.MinHeight = 80;
}
for (int q = 0; q <= colNo; q++)
{
ColumnDefinition Col = new ColumnDefinition();
grid1.ColumnDefinitions.Add(Col);
Col.MinWidth = 128;
}
grid1.Width = 128 * (colNo);
//for loop to add a text block to each cell.
for (int h = 1; h <= rowNo; h++)
{
tbArray[h, 0] = new TextBox() { TextWrapping = TextWrapping.Wrap, AcceptsReturn = Convert.ToBoolean(1) };
tbArray[h, 0].InputScope = new InputScope { Names = { new InputScopeName { NameValue = InputScopeNameValue.Text } } };
tbArray[h, 0].Background = new SolidColorBrush(Colors.Red);
tbArray[h, 0].SetValue(Grid.RowProperty, h);
tbArray[h, 0].SetValue(Grid.ColumnProperty, 0);
grid1.Children.Add(tbArray[h, 0]);
}
for (int h = 1; h <= colNo; h++)
{
tbArray[0,h] = new TextBox() { TextWrapping = TextWrapping.Wrap, AcceptsReturn = Convert.ToBoolean(1) };
tbArray[0, h].InputScope = new InputScope { Names = { new InputScopeName { NameValue = InputScopeNameValue.Text } } };
tbArray[0, h].Background = new SolidColorBrush(Colors.Red);
tbArray[0, h].SetValue(Grid.RowProperty, 0);
tbArray[0, h].SetValue(Grid.ColumnProperty, h);
grid1.Children.Add(tbArray[0, h]);
}
for (int i = 1; i <= rowNo; i++)
{
for (int k = 1; k <= colNo; k++)
{
tbArray[i, k] = new TextBox() { TextWrapping = TextWrapping.Wrap, AcceptsReturn = Convert.ToBoolean(1) };
tbArray[i, k].InputScope = new InputScope { Names = { new InputScopeName { NameValue = InputScopeNameValue.Text } } };
//name each textbox in the grid
tbArray[i, k].Name = string.Format("tb{0}{1}", i, k);
tbArray[i, k].Text = string.Format("afandem{0}{1}", i, k);
//ScrollViewer scroll = new ScrollViewer();
//scroll.SetValue(Grid.RowProperty, i);
//scroll.SetValue(Grid.ColumnProperty, k);
//scroll.Content = tb;
tbArray[i, k].SetValue(Grid.RowProperty, i);
tbArray[i, k].SetValue(Grid.ColumnProperty, k);
grid1.Children.Add(tbArray[i, k]);
}
}
}
private void ApplicationBarIconButton_Click(object sender, EventArgs e)
{
//var isoStore = IsolatedStorageFile.GetUserStoreForApplication();
////For loops to create files
// for (int i = 0; i <= rowNo; i++)
// {
// for (int j = 0; j <= colNo; j++)
// {
// string fileName = string.Format("{0}{1}.txt", i, j);
// using (var file = isoStore.OpenFile(fileName, System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.Write))
// {
// using (var writer = new StreamWriter(file))
// {
// writer.Write(tbArray[i, j].Text);
// }
// }
// }
// }
grid1.Visibility = Visibility.Collapsed;
Grid testGrid = new Grid();
bigGrid.Children.Add(testGrid);
for (int j = 0; j <= rowNo; j++)
{
RowDefinition Row = new RowDefinition();
testGrid.RowDefinitions.Add(Row);
Row.MinHeight = 80;
}
for (int q = 0; q <= colNo; q++)
{
ColumnDefinition Col = new ColumnDefinition();
testGrid.ColumnDefinitions.Add(Col);
Col.MinWidth = 128;
}
testGrid.Width = 128 * (colNo);
for (int i = 0; i <= rowNo; i++)
{
for (int j = 0; j <= colNo; j++)
{
TextBlock tB = new TextBlock();
tB.Text = tbArray[i, j].Text;
tB.SetValue(Grid.RowProperty, i);
tB.SetValue(Grid.ColumnProperty, j);
testGrid.Children.Add(tB);
}
}
}
}
答案 0 :(得分：2)
当您填充tbArray时，您正在使用以下循环
for (int h = 1; h <= rowNo; h++) { ... }
for (int h = 1; h <= colNo; h++) { ... }
由于h在两种情况下都被1初始化为0，因此tbArray[0,0]元素未初始化且为null;因此NullReferenceException。
我不确定你的应用程序应该做什么，但是可能有更好的方法来添加项目，而不是像你正在做的那样在代码隐藏中做所有事情。
例如，如果您在用户点击应用栏按钮时尝试添加其他行，那么您应该使用ListBox而不是Grid。 ItemTemplate的{{1}}将包含一个ListBox，其中包含6列（或Grid水平方向），每个单元格中有一个StackPanel。然后，您可以将每个TextBlock的{{1}}属性绑定到TextBlock，只需向所有集合添加新文本，这将自动更新UI。
如果您使用Google，则有几个关于XAML绑定和Text的教程。此外，除非您在每个ObservableCollection中放置非常少的文字，否则6列对于手机屏幕来说太宽了。