c＃将字符串从公共Form1传递给Private void

Question

I have always used invisible textboxes to pass data in my applications. Now I wanna stop this. So I need to learn how to do this. And right now I'm stuck at the problem passing a string from public Form1() to a private void richTextBox1_KeyDown. I'm not sure how the mechanism works for passing strings.

Here is my code:

public Form1(string file)
{
    InitializeComponent();
    StreamReader sr = new StreamReader(file);
    string filetext = sr.ReadToEnd();
    richTextBox1.Text = filetext;
    string TITLE = file.Split(new string[] { @"\" }, StringSplitOptions.None).Last();
    this.Text = TITLE;
} 

String file will contain something like this if you do: "open with (application)": C:\\Users\\Administrator\\Downloads\\text.tyx If opened the raw .exe file, the string will be empty.

Here is the part I want to catch if string file is empty or not:

private void richTextBox1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.S && e.Control)
    {
        if (Form1(???) != "")
        {
            richTextBox1.SaveFile(Form1(???), RichTextBoxStreamType.PlainText);
        }
    }
}

I put "???" where I have no clue on what to do. Please help

Answer 1

Save fileName as member variable and use it everywhere. Read file using File.ReadAllText(_fileName) :

private readonly string _fileName;

public Form1(string fileName)
{
  InitializeComponent();
  _fileName = fileName;
  richTextBox1.Text = File.ReadAllText(_fileName);
  Text = _fileName.Split(new[] {@"\"}, StringSplitOptions.None).Last();
}

private void richTextBox1_KeyDown(object sender, KeyEventArgs e)
{
  if (e.KeyCode == Keys.S && e.Control)
  {
    if (_fileName == "")
    {
      richTextBox1.SaveFile(_fileName, RichTextBoxStreamType.PlainText);
    }
  }
}

Answer 2

As you show it, your Form1 has a constructor that get a string as parameter. Therefore the code that instantiate your Form1 may look something like:

Form1 form1 = new Form1("Some String");
form1.Show();  //or form1.ShowDialog();

In order to use the string file along your Form1 code, you can define a member variable to the Form1 class as following:

class Form1:Form
{
    private string _file;

    public Form1(string file)
    {
        InitializeComponent();
        _file= file;

        // Your code
    }

}

Now _file is known all along you Form1 and you can use it:

private void richTextBox1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.S && e.Control)
    {
        if (!string.IsNullOrEmpty(_file))
        {
            richTextBox1.SaveFile(_file, RichTextBoxStreamType.PlainText);
        }
    }
}

Answer 3

Regarding the part about wanting to stop using invisible text boxes, I suggest you look into data binding and decoupling business logic and form logic.

But with minimal changes, as the others have stated, you can just store state (the name of the file) on Form1 so it can be accessed in the KeyDown event.