从另一个类访问和修改表单列表框

Question

I'm having some issues accessing and modifying a listbox control from another class.

Here's the MainForm, which holds the listbox:

public partial class MainForm : Form
{
    private static MainForm mainForm = new MainForm();

    internal static MainForm init()
    {
        return MainForm.mainForm;
    }

    public MainForm()
    {
        InitializeComponent();
    }
}

And here's the second class that I'm using to attempt to modify the listbox (the items are added from an event):

public class Utils
{
    void ItemsReceived(object sender, DataReceivedEventArgs<ListboxItems> e)
    {
        MainForm.init().listBox1.Items.Add("test");
    }
}

Using this code setup, nothing is added to the listbox. Any ideas? Or even a better way to tackle this?

Answer 1

Typically visual studio generates the following code in a Program.cs file:

Application.Run(new MainForm());

If this line still exists, your static mainForm variable will hold a different instance of MainForm than the one visible when running the application. If I'm right, change the line in Program.cs to:

Application.Run(MainForm.init());

On a side note, while using the singleton (anti)pattern, consider changing the name of that method to GetInstance() because init() appears to initialize something.