Java realtime writing file when it's opened

Question

I want to write data to file when it's opened, but it doesn't work. Calendar getTime works nice, System.out.println() proves this. Please, any idea, what's wrong...?

Main class:

 public static void main(String[] args) throws IOException {
        // TODO code application logic here
        CurrentTime ct = new CurrentTime();
    }

CurrentTime class:

public class CurrentTime {

    public OutputStream output;
    public InputStream input;
    public Process npp;

    CurrentTime() throws IOException
    {
        Timer t = new Timer();
        npp =  Runtime.getRuntime().exec("notepad");
        output = npp.getOutputStream();        

        TimerTask task = new TimerTask() {
            @Override
            public void run()
            {                 
                String dateStr = Calendar.getInstance(new Locale("ua", "UA")).getTime().toString();
                System.out.println(dateStr);

                try {
                    output.write(dateStr.getBytes());
                    output.flush();                          
                } catch (IOException ex) {                    
                    Logger.getLogger(CurrentTime.class.getName()).log(Level.SEVERE, null, ex);
                }                
            }
        };
        t.schedule(task, 1000, 2000);

    }
}

Maybe this code is wrong in all, np. In this way, I want to discover this moment by any side, is it impossible at all?

UPDATE: it's not actual anymore but just for a note, that time I was trying to implement some kind of tailing operation to the text editor directly and now I understand how abnormal this idea was.. had to be implemented using totally other way of course.

Lupien

"Doesn't work" is BAD. How do you see that it doesn't work? Can you specify it? – Polysynthetic

Why do you think that writing to the stdin of notepad would write to a file? Most Windows applications don't even care about their stdin/stdout. – Trilly

Yes, I can specify it. After launching this program, notepad is opening but then it doesn't output any data, but console is. – Lupien

Actually "I can't make it work" would be a better term. – Rondelle

Answer 1

Interesting:

Lets deal this in simple way.

1. Save a file test.txt somewhere. 
2. Open that file and keep it opened

In Java write to this file (Standard Code)

FileWriter fw = new FileWriter(new FileOutputStream(new File("c:/test.txt")));
fw.write("ABC")

Now go to notepad file again. I normally used Textpad it does refresh automatically (by an alert) because we changed it behind the scene (In your case through Java).

I hope that will clarify a bit.

To be fare trying to excess the genric notepad exe doesn't gurrantee which file you will write in. I am not sure how windows deal with it because you can open 3 different files at one time and which one you will expect to have your data written through java???

Laureen

Answer 2

You're doing it wrong - It's impossible. notepad absolutely ignores it's input while it's running (like most GUI-programs). If you want to show a textbox and write text in it, simply create one with Swing/SWT/...

If you just want to write into a file, just create a new PrintWriter and use it to write files: http://docs.oracle.com/javase/6/docs/api/java/io/PrintWriter.html

Polysynthetic

@user1918648: Yes, It's impossible. – Polysynthetic

Answer 3

You shouldn't try to write through Notepad. Check out PrintWriter.

Apomixis