編輯列表框的內容

Question

我有一個列表框，其中包含各種數據行（基本上是某人正在購買的項目），當用戶單擊某行時，它會在一側填充一個文本框，其數量是多少他買的東西。例如，一行可能是「鉛筆，$ 5，3」，點擊該行使「3」出現在文本框中。

如果用戶改變了3到7，例如，我想，要放回行，所以我們現在有「鉛筆，$ 5，7」

我該怎麼辦呢？

Answer 1

您需要編程列表框的SelectedIndexChanged事件和文本框的TextChanged事件。以下是您的代碼片段：

Private Sub ListBox1_SelectedIndexChanged(_ 
    ByVal sender As System.Object, ByVal e As System.EventArgs) _ 
    Handles ListBox1.SelectedIndexChanged 

    // Exit if no item is selected 
    If ListBox1.SelectedItem Is Nothing Then Exit Sub 

    // Get the item's text 
    Dim item As String = ListBox1.SelectedItem.ToString 

    // Keep only the last part 
    item = item.Substring(item.LastIndexOf(", ") + 2) 

    // Update the textbox 
    TextBox1.Text = item 

End Sub 

Private Sub TextBox1_TextChanged(_ 
    ByVal sender As System.Object, ByVal e As System.EventArgs) _ 
    Handles TextBox1.TextChanged 

    // Exit if no item is selected 
    If ListBox1.SelectedItem Is Nothing Then Exit Sub 

    // Get the item's text, removing the last part 
    Dim item As String = ListBox1.SelectedItem.ToString 
    item = item.Substring(0, item.LastIndexOf(", ") + 2) 

    // Add the numerical value of the textbox's text 
    item &= Val(TextBox1.Text) 

    // Get the index of the selected item 
    Dim index As Integer = ListBox1.SelectedIndex 

    // Remove the old item, add the new one and select it 
    ListBox1.Items.RemoveAt(index) 
    ListBox1.Items.Insert(index, item) 
    ListBox1.SelectedIndex = index 

End Sub