其他形式的调用方法C＃Winforms

Question

I am making a POS system with a C# WinForms application and have a Form1 (main screen) and a Checkout screen (can be thought of as Form2). There is a method in Form1 called clearSale() . I am trying to call it through this button event in Form2 :

private void btnProccessComplete_Click(object sender, EventArgs e)
{
    MessageBox.Show("Order Successfully Processed for: $" + checkoutTotal.ToString("F2"), "Successful Payment", MessageBoxButtons.OK, MessageBoxIcon.Information);
    readyStock(checkoutItems);
    isCheckoutComplete = true;
    Form1 myObj = new Form1();
    myObj.clearSale();
    this.Close();
}

In result of this event finishing it calls the clearSale() method from Form1 :

public void clearSale()
{
    itemList.Items.Clear();
    txtUPCScan.Clear();
    orderTotal = 0.00;
    lblTotalPrice.Text = "$0.00";
    picPay.Enabled = false;
    myShoppingCartItems = null;
    myShoppingCartItems = new string[250];
    totalItems = 0;
}

The clearSale() method pretty much just sets all the txtboxes back to an empty state and makes everything look brand new again. My issue is whenever the clearSale() method gets called in Form1 it will work, but when it is called in Form2 (like I'm trying to get it to) nothing changes on my main page. Like the method almost wasn't called. Everything stays the same and doesn't get cleared. Any help?

Answer 1

If you're creating a new Form1 object it will not reference the previously created ones. Pass Form1 by a constructor parameter to Form2 .

public class Form2: Form{

    Form1 mainObj;

    public Form2(Form1 _mainObj){
        this.mainObj = _mainObj;
    }

    private void btnProccessComplete_Click(object sender, EventArgs e)
    {
        MessageBox.Show("Order Successfully Processed for: $" + checkoutTotal.ToString("F2"), "Successful Payment", MessageBoxButtons.OK, MessageBoxIcon.Information);
        readyStock(checkoutItems);
        isCheckoutComplete = true;
        this.mainObj.clearSale();
        this.Close();
    }
}

From Form1 you now have to create Form2 with:

Form2 checkout = new Form2(this);