c# 文本框显示对象名称而不是值

Question

我有一个用 c# 编写的表单，其中包含各种下拉列表，但我在表单上的列表框方面遇到了问题。当我双击它们时，我需要用从列表框中选择的值填充一个文本框。我的点击事件有效，但文本框只会填充对象名称，而不是列表框中的值

即

'System.Windows.Controls.SelectedItemCollection'

而不是实际值。

这是我正在处理的整个代码块：

我应该在一开始就这样做 - 这是我正在处理的完整代码块：

else if (theValue.FieldName.Equals("UIPathList", StringComparison.OrdinalIgnoreCase) == true)
            {
                int nRow = 14;
                Button theUIPathOptionsButton = new Button();

                TextBox theOldValueTextBox = AddLabelAndOldValue(theHelper, nRow, theValue);
                theOldValueTextBox.Text = theValue.OldValue.Replace(",", "," + Environment.NewLine);

                theUIPathOuterStackPanel = new StackPanel
                {
                    Visibility = Visibility.Visible,
                    Orientation = Orientation.Vertical,
                    Background = new SolidColorBrush(Colors.White),
                    ClipToBounds = true,
                };

                theUIPathOptionsInnerStackPanel = new StackPanel
                {
                    Visibility = Visibility.Visible,
                    Orientation = Orientation.Horizontal,
                    Background = new SolidColorBrush(Colors.White)
                };
                theUIPathOuterStackPanel.ClipToBounds = true;

                TextBox theNewTextBox = new TextBox
                {
                    TabIndex = nRow,
                    TextWrapping = TextWrapping.Wrap,
                    AcceptsReturn = true,
                };

                theNewTextBox.Clear();
                theNewTextBox.MouseDoubleClick += MultiLineChildDatapointList_HandleMouseDoubleClick;
                theNewTextBox.Focusable = true;
                theNewTextBox.HorizontalAlignment = HorizontalAlignment.Stretch;
                theNewTextBox.Width = 365;

                theNewTextBox.PreviewKeyDown += theGetMetadataHelper.Preview_KeyDown_IsMultilineText;

                theNewTextBox.Tag = theValue;

                ListBox theUIPathOptionslistBox = new ListBox();
                theUIPathOptionslistBox.Items.Add("RuntimeDefaults");
                theUIPathOptionslistBox.Items.Add("CommonSettings");
                theUIPathOptionslistBox.Items.Add(InputDatapointManager.CONST_CHANGE_RECORD_CHANGES_CLEAR_VALUE);
                theUIPathOptionslistBox.TabIndex = nRow;
                theUIPathOptionslistBox.SelectionMode = SelectionMode.Multiple;
                theUIPathOptionslistBox.ClipToBounds = true;
                theUIPathOptionslistBox.Focusable = true;
                theUIPathOptionslistBox.Visibility = Visibility.Hidden;
                theUIPathOptionslistBox.Height = 34;

                theUIPathOptionsInnerStackPanel.Children.Add(theNewTextBox);
                theUIPathOptionsInnerStackPanel.Children.Add(theUIPathOptionsButton);

                theUIPathOuterStackPanel.Children.Add(theUIPathOptionsInnerStackPanel);
                theUIPathOuterStackPanel.Children.Add(theUIPathOptionslistBox);

                void button1_click(object sender, EventArgs e)
                {
                    theUIPathOptionslistBox.Visibility = Visibility.Visible;
                }

                void button1_doubleclick(object sender, EventArgs e)
                {
                    theNewTextBox.Text = theUIPathOptionslistBox.SelectedItem.ToString();
                }

                theUIPathOptionsButton.Click += button1_click;
                theUIPathOptionslistBox.MouseDoubleClick += button1_doubleclick;

                Grid.SetColumn(theUIPathOuterStackPanel, 4);
                Grid.SetRow(theUIPathOuterStackPanel, nRow);
                theDataGrid.Children.Add(theUIPathOuterStackPanel);

                theEditControlList.Add(theNewTextBox);
            }

Answer 1

这是因为 TextBox 将对其绑定的内容使用 ToString() 方法，默认情况下将 return class 名称。

您的解决方案是将 class 的 ToString() 方法重写为 return 您想要的值，或者设置 [=10= 的文本属性 ] 到您想要的文本值而不是对象。

Answer 2

ListBox, Item 是对象的集合，不是字符串，所以你必须让它知道如何将它转换为字符串，否则它会使用它的默认 .ToString() 函数，显然你的项目中当前的对象没有给出想要的结果。

假设项目的类型如下 class:

class SomeClass
{
      public int Id;
      public string Name;
}

您可以选择以下三项之一：

1.set 你的 ListBox 的 DisplayMember 到 Name

2.add 将方法覆盖到您的 class 以便它覆盖其 .ToString() 和 return 其名称属性:

class SomeClass
{
      public int Id;
      public string Name;

      public override string ToString()
      {
            return Name;
      }
}

3.Just 将它转换为它的真实类型并得到你想要的属性:

SomeClass selected = (SomeClass)ListBox.SelectedItem;
TextBox1.Text = selected.Name;

Answer 3

这里（可能）已经回答了这个问题：Getting value of selected item in list box as string

string myItem = listBox1.GetItemText(listBox1.SelectedItem);

然后您只需将您的项目添加到文本框即可:

textBox1.Text = myItem;

如果您不想创建新的字符串变量，那么这个也可以：

textBox1.Text = listBox1.SelectedItem.ToString();

Answer 4

最后得到的解决方案如下：

void theUIPathOptionslistBox_SelectedIndexChanged(object sender, 
SelectionChangedEventArgs e)
{
    theNewTextBox.Clear();
    foreach (object selectedItem in theUIPathOptionslistBox.SelectedItems)
    {
        theNewTextBox.AppendText(selectedItem.ToString() + Environment.NewLine);
    }
}
theUIPathOptionslistBox.SelectionChanged += 
theUIPathOptionslistBox_SelectedIndexChanged;

c# 文本框显示对象名称而不是值

c# textbox shows object name instead of value

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