File is being used by another process

Question

I have a program that roughly does this:

1. open a file to read from it.
2. close the file
3. Start a filewatcher to watch for changes in the file.

Answer 1

If your code is similar to this:

[STAThread]
static void Main(string[] args)
{
    string file = "temp.txt";
    ReadFile(file);
    FileSystemWatcher fswatcher = new FileSystemWatcher(".\\");
    fswatcher.Changed += delegate(object sender, FileSystemEventArgs e)
                             {
                                 ReadFile(e.FullPath);
                             };
    while (true)
    {
        fswatcher.WaitForChanged(WatcherChangeTypes.Changed);
    }
}
private static void ReadFile(string file)
{
    Stream stream = File.OpenRead(file);
    StreamReader streamReader = new StreamReader(stream);
    string str = streamReader.ReadToEnd();
    MessageBox.Show(str);
    streamReader.Close();
    stream.Close();
}

If you are editing the file via notepad, then, when you click the save button, it keeps the file open, while as if when you just close the program and click save it doesn't. I do no know if this is a bug or an undocumented feature of notepad, but this just might be your problem. One way to fix this is to do the following:

In your anonymous delegate, or wherever you execute the call to ReadFile() call Thread.Sleep(1000), to have the program wait before reading the file and your code should work fine.