How can I change label text in different class (C#)

Question

Please, you can you help me, how can i change label text in diferent class?

Basic winform script:

public partial class buildEditor : Form
{
    public buildEditor()
    {
        InitializeComponent();
        Label maxSkillPoint = new Label();
        maxSkillPoint.AutoSize = true;
        maxSkillPoint.BackColor = System.Drawing.Color.Transparent;
        maxSkillPoint.Font = new System.Drawing.Font("Microsoft Sans Serif", 12F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(238)));
        maxSkillPoint.ForeColor = System.Drawing.Color.FromArgb(((int)(((byte)(193)))), ((int)(((byte)(196)))), ((int)(((byte)(181)))));
        maxSkillPoint.Location = new System.Drawing.Point(528, 687);
        maxSkillPoint.Name = "maxSkillPoint";
        maxSkillPoint.Text = UniqueValue.spentSkillPoints.ToString();
        maxSkillPoint.Size = new System.Drawing.Size(0, 20);
        this.Controls.Add(maxSkillPoint);
    }

    public void maxSkillPoint_TextChanged(Form formInstance, string labelName)
    {
        // Get reference to the label
        var label = formInstance.Controls.Find(labelName, true).FirstOrDefault();
        if (null != label && label is Label)
        {
            (label as Label).Text = "test";
        }
    }
}

I created next class which will be change text for maxSkill text.

public class ChangeTextForMaxSkill()
{
    Button button = new Button();

    public ChangeTextForMaxSkill()
    {
        button.Click += new EventHandler(changeText);
    }

    private void changeText(object sender, EventArgs e)
    {
        // Get reference to the label
        var buildEditor = new buildEditor();
        buildEditor.maxSkillPoint_TextChanged(buildEditor, "maxSkillPoint");
    }
}

I really thx for all answers.

Answer 1

I got it very simple: Hand over the Label control in the constructor of your external class:

using System.Windows.Forms;

public class Yourclass{

    private Label UpdateLabel;
    public Yourclass (Label yourLabel)
    {
        this.UpdateLabel = yourlabel;
    }

    private void action()
    {
        //here is your update of the label
        UpdateLabel.Text = "Your text";
    }

}

In the form class, create an instance of "yourclass" and hand over the Label:

Yourclass cls = new Yourclass(Label1);

Answer 2

First of all your naming conventions do not follow standard practices. Both class and method names should use uppercase first letters of words, not camel case as you have done. I have used proper naming conventions in my answer.

You have to pass an instance of your BuildEditor* form to your ChangeTextForMaxSkill.ChangeText() function.

Next, the label object maxSkill is not a property of your BuildEditor class. Therefore, you'd need to actually find a reference to that control within the form since you're dynamically adding it.

public partial class BuildEditor : Form
{
    public BuildEditor()
    {
        InitializeComponent();

        Label maxSkill = new Label();
        maxSkill.Name = "MaxSkil"; // need the ID to find it later (makes it easier)
        maxSkill.Location = new Point(1, 1);
        this.Controls.Add(maxSkill);
    }

    // This is just for testing; assumes you dragged a button from toolbox onto your
    // BuildEditor form in the Form Designer
    private void button1_Click(object sender, EventArgs e)
    {
        var changeTextForMaxSkill = new ChangeTextForMaxSkill();
        changeTextForMaxSkill.ChangeText(this, "MaxSkil");
    }

}

public class ChangeTextForMaxSkill
{
    public void ChangeText(Form formInstance, string labelName)
    {
        // Get reference to the label
        var label = formInstance.Controls.Find(labelName, true).FirstOrDefault();
        if (null != label && label is Label)
        {             
            (label as Label) .Text = "test";
        }
    }
}

If you want to test it, just add a button on your form and make the test in the button click handler:

private void button1_Click(object sender, EventArgs e)
{
    var changeTextForMaxSkill = new ChangeTextForMaxSkill();
    changeTextForMaxSkill.ChangeText(this, "MaxSkil");
}

I've tested and this works :)