如何给另一个类别的财产赋予价值

Question

I have 2 classes: FrmMenu and FrmProperty . In FrmProperty I created a property like this:

public string ApplicationString { get; set; }

form1_load(object sender, EventArgs e)
{
    MessageBox.Show(ApplicationString);
}

Then, I instantiate that class in FrmMenu , like this:

FrmProperty frmp = new FrmProperty();
//Give value
frmp.ApplicationString = "1";
frmp.ShowDialog();

This code should transfer a value from FrmMenu to FrmProperty . Why doesn't this work? The MessageBox is blank.

Answer 1

So, I've tried this out myself and the first thing to note is that the code you supply does not compile. Your example has:

form1_load(object sender, EventArgs e)
{
    MessageBox.Show(ApplicationString);
}

but this would be better writen as:

private void FrmProperty_Load(object sender, EventArgs e)
{
    MessageBox.Show(ApplicationString);
}

Perhaps that is self explanatory but I find it always helps to make sure everything is as clear as possible.

In terms of your problem, the only thing I can possibly think of that would make your code fail to work using the above is if you had not wired up the FrmProperty_Load method to the Load event of FrmProperty .

The FrmProperty_Load method won't run unless something asks it to, so in the constructor for FrmProperty add the following:

this.Load += FrmProperty_Load;

Your FrmMenu class should remain unchanged and your FrmProperty class should look roughly like the following:

public partial class FrmProperty : Form
{
    public string ApplicationString { get; set; }

    public FrmProperty()
    {
        InitializeComponent();
        this.Load += FrmProperty_Load;
    }

    private void FrmProperty_Load(object sender, EventArgs e)
    {
        MessageBox.Show(ApplicationString);
    }

}