MenuItem.Checked 属性

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

获取或设置一个值，通过该值指示选中标记是否出现在菜单项文本的旁边。

public:
 property bool Checked { bool get(); void set(bool value); };

public bool Checked { get; set; }

member this.Checked : bool with get, set

Public Property Checked As Boolean

属性值

Boolean

如果菜单项旁边有一个选中标记，则为 true；否则为 false。 默认值为 false。

例外

ArgumentException

MenuItem 是顶级菜单，或有子级。

示例

下面的代码示例使用 Checked 属性在应用程序中提供状态。 在此示例中，一组菜单项用于指定控件中 TextBox 文本的颜色。 提供的事件处理程序由 Click 三个菜单项的事件使用。 每个菜单项指定一种文本颜色， menuItemRed (红色) 、 menuItemGreen (绿色) 或 menuItemBlue (蓝色) 。 事件处理程序确定单击了哪个菜单项，在所选菜单项上放置复选标记，并更改窗体 TextBox 控件的文本颜色。 该示例要求 System.Drawing 命名空间已添加到此代码所在的窗体中。 该示例还要求 TextBox 已将 添加到此示例代码所在的窗体中，名为 textBox1。

private:
   // The following event handler would be connected to three menu items.
   void MyMenuClick( Object^ sender, EventArgs^ e )
   {
      // Determine if clicked menu item is the Blue menu item.
      if ( sender == menuItemBlue )
      {
         // Set the checkmark for the menuItemBlue menu item.
         menuItemBlue->Checked = true;
         // Uncheck the menuItemRed and menuItemGreen menu items.
         menuItemRed->Checked = false;
         menuItemGreen->Checked = false;
         // Set the color of the text in the TextBox control to Blue.
         textBox1->ForeColor = Color::Blue;
      }
      else if ( sender == menuItemRed )
      {
         
         // Set the checkmark for the menuItemRed menu item.
         menuItemRed->Checked = true;
         // Uncheck the menuItemBlue and menuItemGreen menu items.
         menuItemBlue->Checked = false;
         menuItemGreen->Checked = false;
         // Set the color of the text in the TextBox control to Red.
         textBox1->ForeColor = Color::Red;
      }
      else
      {
         // Set the checkmark for the menuItemGreen.
         menuItemGreen->Checked = true;
         // Uncheck the menuItemRed and menuItemBlue menu items.
         menuItemBlue->Checked = false;
         menuItemRed->Checked = false;
         // Set the color of the text in the TextBox control to Blue.
         textBox1->ForeColor = Color::Green;
      }
   }

// The following event handler would be connected to three menu items.
 private void MyMenuClick(Object sender, EventArgs e)
 {
    // Determine if clicked menu item is the Blue menu item.
    if(sender == menuItemBlue)
    {
       // Set the checkmark for the menuItemBlue menu item.
       menuItemBlue.Checked = true;
       // Uncheck the menuItemRed and menuItemGreen menu items.
       menuItemRed.Checked = false;
       menuItemGreen.Checked = false;
       // Set the color of the text in the TextBox control to Blue.
       textBox1.ForeColor = Color.Blue;
    }
    else if(sender == menuItemRed)
    {
       // Set the checkmark for the menuItemRed menu item.
       menuItemRed.Checked = true;
       // Uncheck the menuItemBlue and menuItemGreen menu items.
       menuItemBlue.Checked = false;
       menuItemGreen.Checked = false;
       // Set the color of the text in the TextBox control to Red.
       textBox1.ForeColor = Color.Red;
    }
    else
    {
       // Set the checkmark for the menuItemGreen.
       menuItemGreen.Checked = true;
       // Uncheck the menuItemRed and menuItemBlue menu items.
       menuItemBlue.Checked = false;
       menuItemRed.Checked = false;
       // Set the color of the text in the TextBox control to Blue.
       textBox1.ForeColor = Color.Green;
    }
 }

' The following event handler would be connected to three menu items.
Private Sub MyMenuClick(sender As Object, e As EventArgs)
    ' Determine if clicked menu item is the Blue menu item.
    If sender Is menuItemBlue Then
        ' Set the checkmark for the menuItemBlue menu item.
        menuItemBlue.Checked = True
        ' Uncheck the menuItemRed and menuItemGreen menu items.
        menuItemRed.Checked = False
        menuItemGreen.Checked = False
        ' Set the color of the text in the TextBox control to Blue.
        textBox1.ForeColor = Color.Blue
    Else
        If sender Is menuItemRed Then
            ' Set the checkmark for the menuItemRed menu item.
            menuItemRed.Checked = True
            ' Uncheck the menuItemBlue and menuItemGreen menu items.
            menuItemBlue.Checked = False
            menuItemGreen.Checked = False
            ' Set the color of the text in the TextBox control to Red.
            textBox1.ForeColor = Color.Red
        Else
            ' Set the checkmark for the menuItemGreen.
            menuItemGreen.Checked = True
            ' Uncheck the menuItemRed and menuItemBlue menu items.
            menuItemBlue.Checked = False
            menuItemRed.Checked = False
            ' Set the color of the text in the TextBox control to Blue.
            textBox1.ForeColor = Color.Green
        End If
    End If
End Sub

注解

可以将 Checked 属性与菜单中的其他菜单项结合使用，为应用程序提供状态。 例如，可以在一组项的菜单项上放置一个检查标记，以标识要为应用程序中的文本显示的字体大小。 还可以使用 Checked 属性来标识一组互斥菜单项中的所选菜单项。

注意

对于顶级菜单项，此属性不能设置为 true 。