同时从2种不同形式的输出中更新2种不同的标签

Question

我有2种形式，它们都具有label1，form1和form2 label1必须显示相同的输出，当我单击form1上的按钮时，form1中的label1将会更改，以便form2中的label1

Form1

        SqlDataReader reader = cmdnext.ExecuteReader();
        while (reader.Read())
        {
            label1.Text = reader[0].ToString();
            break;

        }
        sqlcon.Close();

        Lobbypage lp = new Lobbypage(label1.Text);

    }

Form2

     public Lobbypage(string labelText)
    {
        InitializeComponent();
        label1.Text = labelText;

    }

跳过按钮

private void button1_Click(object sender, EventArgs e)
    {
        sqlcon.Open();
        SqlCommand cmdcurrent = sqlcon.CreateCommand();
        cmdcurrent.CommandType = CommandType.Text;
        cmdcurrent.Parameters.Add("@Title", SqlDbType.VarChar).Value = title;
        cmdcurrent.CommandText = "update tblQLCashier set status = 'missing' where queID = (select min(queID) from tblQLCashier where status = 'On process' and department = @Title)";
        cmdcurrent.ExecuteNonQuery();

        SqlCommand cmdnext = sqlcon.CreateCommand();
        cmdnext.CommandType = CommandType.Text;
        cmdnext.Parameters.Add("@Title", SqlDbType.VarChar).Value = title;
        cmdnext.CommandText = "update tblQLCashier set status = 'On process' , department = @Title where queID = (select min(queID) from tblQLCashier where status = 'Pending' and department ='')";
        cmdnext.ExecuteNonQuery();
        sqlcon.Close();

        sqlcon.Open();
        cmdnext.CommandText = "select queID from tblQLCashier where queID = (select min(queID) from tblQLCashier where department in ('', @Title) and status in ('Pending', 'On process'))";
        SqlDataReader reader = cmdnext.ExecuteReader();
        while (reader.Read())
        {
            label1.Text = reader[0].ToString();
            break;

        }
        sqlcon.Close();

        Lobbypage lp = new Lobbypage(label1);

    }

form1和form2中的label1应该同时更新并具有相同的输出

Answer 1

在Form2中

public Lobbypage(Label label)
{
    InitializeComponent();
    label1 = label;
}

在Form1

Lobbypage lp = new Lobbypage(label1);

那是怎么回事？在label1的构造函数中提供Lobbypage时，它将创建一个新变量（label），它是label1的副本。 “技巧”是label1实际上是一个引用，因此副本也将指向相同的标签对象。

Answer 2

您可以创建一个静态字符串属性，并将其分配给两个标签。

Answer 3

为什么不公开标签，这是对我有用的代码：

namespace WindowsFormsApp1
{
public partial class Form2 : Form
{
    static public Label label2 = new Label();

    public Form2()
    {
        InitializeComponent();
    }

    private void Form2_Load(object sender, EventArgs e)
    {
        label2.Location = new Point(20, 20);
        Controls.Add(label2);
        label2.Text = "mama";
    }
}
}

其他表格

namespace WindowsFormsApp1
{
public partial class Form1 : Form
{

    public Form1()
    {

        Form2 hi = new Form2();
        hi.Show();
        InitializeComponent();
    }

    private void button1_Click_1(object sender, EventArgs e)
    {
        Form2.label2.Text = "Mathman";

    }
}
}

确保将功能添加到处理程序。这意味着不仅仅是复制粘贴。Dubble单击表格以自动添加加载功能 after Click before Click