如何從列表框C＃中刪除所選項目

Question

我目前正在嘗試查看用戶在列表框中選擇的所有文件和文件夾。 現在，我能夠使用openfiledialogue列出用戶選擇的內容，但是當我嘗試從列表框中刪除它時，我現在正面臨問題。 我試圖允許用戶單擊文件旁邊的復選框，然后按“刪除”按鈕將其刪除

這是我的刪除按鈕代碼

      private void button2_Click(object sender, EventArgs e)
    {
        for (int i = listView1.SelectedItems.Count - 1; i >= 0; i--)
        {
            listView1.Items.Remove(listView1.SelectedItems[i]);
        }

    }

這是添加到列表框中以供參考的jsut文件，以防萬一

    private void button1_Click(object sender, EventArgs e)
    {

        OpenFileDialog openfiledialog = new OpenFileDialog();
        // Display open file dialog
        openfiledialog.InitialDirectory = "C:\\";
        //openfiledialog.Multiselect = true;
        openfiledialog.Title = "Lock File";
        openfiledialog.Filter = "All Files | *.*";
        openfiledialog.ShowDialog();


        if (openfiledialog.FileName != "")
        {

        //move through FileInfo array and store in new array of fi
            listView1.Items.Clear();
            foreach (string file in openfiledialog.FileNames)
            {
                listView1.Items.Add(file);
            }        
        }

    }

並且我按下了刪除按鈕，什么也沒有發生，我在Google上看到關於使用selectionmode的一些答案，但是當我使用它時，我的列表框不具有selectionmode的屬性，並且用紅線標記了下划線

Answer 1

您的問題是因為SelectedItems屬性實際上是對Items集合的引用，並且您在對其進行迭代時更改了該集合。 試試下面的代碼

listView1.BeginUpdate();
ArrayList vSelectedItems = new ArrayList(listView1.SelectedItems);
foreach (string item in vSelectedItems)
{
   listView1.Items.Remove(item);
}
listView1.EndUpdate();

BeginUpdate()和EndUpdate()方法將優化此操作的性能-在這些方法調用之間的活動期間，listView不會刷新自身。

Answer 2

不要使用listView1.SelectedItems而是使用listView1.CheckedItems並將button2_click更改為：

private void button2_Click(object sender, EventArgs e)
        {
            foreach (ListViewItem i in listView1.CheckedItems)
                listView1.Items.Remove(i);

        }

Answer 3

while (listView1.SelectedItems.Count > 0)
{
    listView1.Items.Remove(listView1.SelectedItems[0]);
}

Answer 4

嘗試這個

   private void button2_Click(object sender, EventArgs e)
        {
           for(int i = 0 ; i < listView1.SelectedItems.Count; i ++)
               listView1.Items.Remove(listView1.SelectedItems[i]);

        }

Answer 5

$x = @()

[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing") 

$objForm = New-Object System.Windows.Forms.Form 
$objForm.Text = "hello first"
$objForm.Size = New-Object System.Drawing.Size(600,600) 
$objForm.StartPosition = "CenterScreen"

$objForm.KeyPreview = $True

$objForm.Add_KeyDown({if ($_.KeyCode -eq "Enter") 
    {
        foreach ($objItem in $objListbox.SelectedItems)
            {$x += $objItem}
        $objForm.Close()
    }
    })

$objForm.Add_KeyDown({if ($_.KeyCode -eq "Escape") 
    {$objForm.Close()}})

$OKButton = New-Object System.Windows.Forms.Button
$OKButton.Location = New-Object System.Drawing.Size(10,250)
$OKButton.Size = New-Object System.Drawing.Size(85,30)
$OKButton.Text = "Start Check"

$MoveRight = New-Object System.Windows.Forms.Button
$MoveRight.Location = New-Object System.Drawing.Size(200,80)
$MoveRight.Size = New-Object System.Drawing.Size(70,20)
$MoveRight.Text = ">>"

$objForm.Controls.Add($MoveRight)


$MoveRight.Add_Click(
   {
        foreach ($objItem in $objListbox.SelectedItems)
            {[void] $objListbox2.Items.Add($objItem)}


            $selectedItems = $objListbox.SelectedItems;

if ($objListbox.SelectedIndex -ne -1)
{ 
    for ($i = $selectedItems.Count - 1; $i -ge 0; $i--){$objListbox.Items.Remove($SelectedItems[$i])}
}
})

$MoveLeft = New-Object System.Windows.Forms.Button
$MoveLeft.Location = New-Object System.Drawing.Size(200,120)
$MoveLeft.Size = New-Object System.Drawing.Size(70,20)
$MoveLeft.Text = "<<"

$objForm.Controls.Add($MoveLeft)

$MoveLeft.Add_Click(
   {

        foreach ($objItem in $objListbox2.SelectedItems)
            {[void] $objListbox.Items.Add($objItem)
        }


            $selectedItems = $objListbox2.SelectedItems;

if ($objListbox2.SelectedIndex -ne -1)
{ 
    for ($i = $selectedItems.Count - 1; $i -ge 0; $i--){$objListbox2.Items.Remove($SelectedItems[$i])}
}

})

$Clearconsole = New-Object System.Windows.Forms.Button
$Clearconsole.Location = New-Object System.Drawing.Size(505,320)
$Clearconsole.Size = New-Object System.Drawing.Size(70,20)
$Clearconsole.Text = "Clr console"

$objForm.Controls.Add($Clearconsole)

$Clearconsole.Add_Click(
   {
     $outputBox.Clear()

   })

$MoveAll = New-Object System.Windows.Forms.Button
$MoveAll.Location = New-Object System.Drawing.Size(200,160)
$MoveAll.Size = New-Object System.Drawing.Size(70,20)
$MoveAll.Text = "ALL"

$objForm.Controls.Add($MoveAll)


$MoveAll.Add_Click(
   {
        foreach ($objItem in $objListbox.Items)
            {[void] $objListbox2.Items.Add($objItem)}


$objListbox.Items.Clear()
    $outputBox.text="test"
   })

$objLabel = New-Object System.Windows.Forms.Label
$objLabel.Location = New-Object System.Drawing.Size(10,320) 
$objLabel.Size = New-Object System.Drawing.Size(280,20) 
$objLabel.Text = "Console Window"
$objForm.Controls.Add($objLabel) 

$outputBox = New-Object System.Windows.Forms.TextBox 
$outputBox.Location = New-Object System.Drawing.Size(10,350) 
$outputBox.Size = New-Object System.Drawing.Size(565,200) 
$outputBox.MultiLine = $True 

$outputBox.ScrollBars = "Vertical" 

$objForm.Controls.Add($outputBox) 

$OKButton.Add_Click(
   {
        foreach ($objItem in $objListbox.SelectedItems)
            {$x += $objItem}
        $objForm.Close()
   })

$objForm.Controls.Add($OKButton)

$objLabel = New-Object System.Windows.Forms.Label
$objLabel.Location = New-Object System.Drawing.Size(10,20) 
$objLabel.Size = New-Object System.Drawing.Size(280,20) 
$objLabel.Text = "Please make a selection from the list below:"
$objForm.Controls.Add($objLabel) 

$objListbox = New-Object System.Windows.Forms.Listbox 
$objListbox.Location = New-Object System.Drawing.Size(10,40) 
$objListbox.Size = New-Object System.Drawing.Size(160,20) 

$objListbox.SelectionMode = "MultiExtended"

[void] $objListbox.Items.Add("a")
[void] $objListbox.Items.Add("b")
[void] $objListbox.Items.Add("c")
[void] $objListbox.Items.Add("d")
[void] $objListbox.Items.Add("e")

$objListbox.Height = 200
$objListBox.Sorted = $True
$objForm.Controls.Add($objListbox) 
$objForm.Topmost = $True

$objListbox2 = New-Object System.Windows.Forms.Listbox 
$objListbox2.Location = New-Object System.Drawing.Size(315,40) 
$objListbox2.Size = New-Object System.Drawing.Size(160,20) 

$objListbox2.SelectionMode = "MultiExtended"

$objListbox2.Height = 200
$objListBox2.Sorted = $True
$objForm.Controls.Add($objListbox2) 
$objForm.Topmost = $True

$objForm.Add_Shown({$objForm.Activate()})
[void] $objForm.ShowDialog()

$x