Question

它的可能性例如：

表单以1个文本框（名称：textbox1）和1个标签（名称：label1）开头在运行时创建文本框和标签（侧面），所以在运行时我们可以有

label1 - textbox1
label2 - textbox2
label3 - textbox3
label4 - textbox4

如何在编译可执行文件之前在代码中引用这些期货文本框/标签而不会出现这些文本框/标签不存在的错误？（

只有每个人都知道，我以这种方式在运行时创建新的文本框和标签：

            n++;
            TextBox txt = new TextBox();
            txt.Name = "textbox" + n;
            txt.Text = "";
            txt.Size = new System.Drawing.Size(189, 26);
            txt.Location = new Point(87, n2);
            testelogico = txt.Name;
            gpbCategoria.Controls.Add(txt);
            txt.TextChanged += new EventHandler(new_onchange);
            txt.Leave += new EventHandler(erase_onLeave);

            Label lbl = new Label();
            lbl.Name = "label" + n;
            lbl.Text = "Acessório Nº" + n + ":";
            lbl.Location = new Point(4, n2 + 5);
            gpbCategoria.Controls.Add(lbl);

在代码的另一部分，我想举例说明：

If (textbox4.Text == "" && label4.Name == "Acessório Nº4:")
{
gpbCategoria.Controls.Remove(textbox4);
gpbCategoria.Controls.Remove(label4);
}

但我会有错误，因为这些标签尚不存在（只会在运行时创建）

Answer 1

您正在动态生成控件，因此编译器在创建它之前不知道textBox4是什么。您可以做的是在运行时通过其名称搜索该控件：

TextBox textbox4 = (TextBox)this.Controls.Find("textbox4", false).FirstOrDefault();

if (textbox4 == null)
{
    throw new Exception("Could not find textbox4.");
}

这将在textbox4中搜索Form.Controls，如果不存在则会抛出异常。您可以对labels或表单中的任何其他控件使用相同的模式。

Answer 2

您可以按名称找到文本框：

var textbox = this.Controls.OfType<TextBox>().Single(ctr => ctr.Name == "textboxname");

Answer 3

如果您使用的是.Net framework 4.0或更高版本，则可以使用动态关键字：以下是完整的代码供您参考：

public class Class1
{
    // Declare all the controls as dynamic
    dynamic textbox1, textbox2, textbox3, textbox4;
    dynamic label1, label2, label3, label4;

    public Class1()
    {
        // Create the actual object type, which they will hold at Run time. 
        textbox1 = textbox2 = textbox3 = textbox4 = new TextBox();
        label1 = label2 = label3 = label4 = new Label();

        // Loop through to create controls at Runtime.
        n++;
        TextBox txt = new TextBox();
        txt.Name = "textbox" + n;
        txt.Text = "";
        txt.Size = new System.Drawing.Size(189, 26);
        txt.Location = new Point(87, n2);
        testelogico = txt.Name;
        gpbCategoria.Controls.Add(txt);
        txt.TextChanged += new EventHandler(new_onchange);
        txt.Leave += new EventHandler(erase_onLeave);

        Label lbl = new Label();
        lbl.Name = "label" + n;
        lbl.Text = "Acessório Nº" + n + ":";
        lbl.Location = new Point(4, n2 + 5);
        gpbCategoria.Controls.Add(lbl);

    }

    public void Foo()
    {
        //Throw exception if controls are not initialized yet.
        if (textbox4 == null || label4 == null)
        {
            throw new Exception("Controls not initialized.");
        }

        else
        {
            // You can access the control propoties similar to normal controls.
            if (textbox4.Text == "" && label4.Name == "Acessório Nº4:")
            {
                gpbCategoria.Controls.Remove(textbox4);
                gpbCategoria.Controls.Remove(label4);
            }
        }
    }
}

Answer 4

将Label - TextBox削减放入UserControl会好得多。

让UserControl具有通过构造函数

的索引号

   public class MyUserControl : UserControl 
   {
      private readonly int index;

      public MyUserControl(int index)
      {
         this.index = index;

         InitializeComponent(); // will init you sub controls: label and textbox

         // set name to label

      } 

      public int Index
      {
         get { return index; }
      } 
   }

使用已建议的方法通过Controls集合中的索引查找用户控件，如果找到则将其删除。

Answer 5

嗨@ programmer93和@Jonesy，感谢您的帮助，现在它正常工作，看看我的最终代码（可以帮助那些有同样疑问的人）

    TextBox txtAcessorio4 = (TextBox)gpbCategoria.Controls.Find("txtAcessorio4", false).FirstOrDefault();
Label lblAcessorio4 = (Label)gpbCategoria.Controls.Find("lblAcessorio4", false).FirstOrDefault();

                    if (txtAcessorio4 != null && txtAcessorio4.Text == "" && lblAcessorio4.Name == "lblAcessorio4")
                    {
                        MessageBox.Show("Perfect");                           
                    }

C＃Windows窗体 - 如何在运行时新文本框/侧面标签中创建引用（也在运行时创建）？

5 个答案: