C# Call a method from a different form class?

问题

Ok, so I have a method in one class and I'm trying to call it from another class.

Form1:

    public void ChangeBack(Color clr)
    {
        this.BackColor = clr;
    }

Form2:

    public void ChangBackColor_Click(object sender, EventArgs e)
    {
        if (ColorDialog.ShowDialog() == DialogResult.OK)
        {
            Form1.ChangeBack(ColorDialog.Color);
        }
    }

But I need to make the ChangeBack method static to be able to call it. So:

Form1:

    public static void ChangeBack(Color clr)
    {
        this.BackColor = clr;
    }

But then I can't use "this." as the void doesn't allow it because it's static. And I can't create a new form1 because it needs to run overall in two windows.

Please help!C

回答1:

When you are working with multiple forms, you need to pass a reference to the second form, so that it "knows" about the first form. To do this you will need to change the constructor of your second form, and add a private reference to that form, like so:

class Form2 : Form
{
    //Variables
    private Form1 _ParentForm; //Add this here

    //Constructor
    public Form2(Form1 parentForm)
    {
        InitalizeComponent();
        _ParentForm = parentForm; //Add this here
    }
}

The, when you create the second form on your main form, you can use this to pass the reference of itself on to the new form:

class Form1 : Form
{

    public void ChangeBack(Color clr) //No longer needs to be static
    {
        this.BackColor = clr;
    }

    public void CreateSecondForm()
    {
        Form2 secondForm = new Form2(this);
        secondForm.Show();
    }
}

Then you can call any function on the parent form (i.e. Form1) from the second form like so:

public void ChangBackColor_Click(object sender, EventArgs e)
{
    if (ColorDialog.ShowDialog() == DialogResult.OK)
    {
        //Access Form1's reference with _ParentForm instead of Form1
        _ParentForm.ChangeBack(ColorDialog.Color);
    }
}

回答2:

If you work with 2 different WinForm windows you should simply pass a reference from one window to the other (typically using constructor). For instance:

var childForm = new ChildForm(this); // where this is your main WinForm

after that you can use the reference to the main WinForm to call it's methods.

回答3:

That's correct, you cannot make the method static and access instance of the object.

Change BackColor to a static property or change your method to a non static one

来源：https://stackoverflow.com/questions/33193504/c-sharp-call-a-method-from-a-different-form-class

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.net

winforms

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methods