c# - 在c#中检查flowLayoutPanel是否为空

Question

当我的 flowLayoutPanel 为空时，我想制作一个错误标签，但我不知道如何检查 flowLayoutPanel 是否为空。这是我当前的代码：

private void flowLayoutPanel1_ControlRemoved(object sender, ControlEventArgs e)
        {
            if (flowLayoutPanel1.Controls == null)
            {
                customtoolwarning.Visible = true;
            }
            else
            {
                customtoolwarning.Visible = false;
            }
        }

请帮忙，

谢谢

Answer 1

private void flowLayoutPanel1_ControlRemoved(object sender, ControlEventArgs e)
        {
            if (flowLayoutPanel1.Controls.Count > 0)
            {
                customtoolwarning.Visible = true;
            }
            else
            {
                customtoolwarning.Visible = false;
            }
        }

Answer 2

您遇到的问题是您正在检查Controls以null确定它是否为空。该Controls属性永远不会是null，而是将是非空的，并且在为空时长度为 0。例如

if (flowLayoutPanel1.Controls.Count == 0) {
  // It's empty
}

Answer 3

lblNoContacts.Visible = (flowLayoutPanel.Controls.Count == 0) ? true : false;