create a text file in java

Question

I have a problem about creating a textfile with the name I want.

I want to create a textfile named : 'username' Subjects.

 private void saveSubjects(){

    RegisterFrame r = new RegisterFrame();


    String username = r.txtUser.getText();;

    try{
        FileWriter f = new FileWriter(username + "" + "Subjects" + ".txt", true);

        String subjects[] = lstSubjects.getItems();

        for(int i = 0; i<subjects.length; i++){
            f.write(subjects[i] + "\r\n");
        }
        f.close();
        JOptionPane.showMessageDialog(null, "Data saved!", "Data Saved", JOptionPane.INFORMATION_MESSAGE);
    }catch(Exception e){
        JOptionPane.showMessageDialog(null, "Nothing Inputted!", "Error", JOptionPane.ERROR_MESSAGE);
    }

}

I want to get the username from RegisterFrame as it is inputted there but it's not working. I know it's a simple thing but I'm still a beginner in this. How can I solve this?

Thanks in advance

is username always blank? It looks like you may not be getting it properly from you RegisterFrame class — RNJ
– RNJ, Commented Sep 12, 2012 at 15:02
Did you any error or exceptions? if so please post that messages also. — Ami
– Ami, Commented Sep 12, 2012 at 15:02
How isn't it working? Do you get errors? You have a syntax error on the line where you define username (double ;;). — scrappedcola
– scrappedcola, Commented Sep 12, 2012 at 15:03
As others have commented, we need more information. Check out this link for some tips on how to fill in the rest of the details. In particular, we need some details about what exactly isn't working. Does your code compile? If not, what are the error messages? If so, what happens when it runs? Again, give us any error messages and/or the output and explain why it isn't what you want. — Code-Apprentice
– Code-Apprentice, Commented Sep 12, 2012 at 15:05

dimo414 · Accepted Answer · 2016-06-04 04:15:19Z

2

try this:

String username = r.txtUser.getText();
System.out.println("The loaded username is: " + username);

then you will see where your problem is : writing into the file OR getting the username text.

If the problem is in getting the text, consider other way of getting it or modify the question by removing the file write part and specifiing the username getting part.

Otherwise, IDK where the error is.

BTW: how is it not working? the file is not created at all? do you see any errors? the file has wrong name? please specify

edited Jun 4, 2016 at 4:15

dimo414

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answered Sep 12, 2012 at 15:17

kajacx

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Comments

Edd · Accepted Answer · 2012-09-12 15:25:42Z

0

Your code for writing the file seems to be fine. Based on your code I tried this which worked perfectly:

public static void main(String[] args) {

    FileWriter f = null;
    try {
        f = new FileWriter("Subjects.txt", true);

        String subjects[] = {"subject1", "subject2"};

        for (String subject : subjects) {
            f.write(subject + "\r\n");
        }

    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        IOUtils.closeQuietly(f);
    }
}

I'd say your problem is elsewhere.

Please note that best practice dictates that Closeable objects such as FileWriter should be closed in a finally block

answered Sep 12, 2012 at 15:25

Edd

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Comments

dimo414 · Accepted Answer · 2012-09-12 15:34:04Z

Assuming new RegisterFrame() starts up a GUI window, the issue is your code runs before you have a chance to type in your name. Instead you need to use event listeners to capture the contents of text fields, otherwise the code to get the name runs immediately after the window opens, long before you have a chance to type anything in.

The timeline is like this:

RegisterFrame starts a new thread to display the GUI without blocking your code
Your code immediately pulls "" from txtUser, which is of course empty
Now you type your name in
Nothing happens, because nothing in your code is paying attention to that action

Instead, it should be:

RegisterFrame starts a new thread to display the GUI without blocking your code
The method returns, or starts doing work that isn't dependent on the GUI
Now you type your name in
An event listener is triggered from the new thread, and the associated action to get the name and write to a file is executed

You have to decide what sort of listener makes sense for your use case, for instance you might want to wait until the user clicks a button (that says "Submit" or "Write File" for instance) and register an ActionListener on that button. Then you put your username polling and file writing behavior in that action* and you're golden!

_{*I should add that in truth you want to do as little as possible in ActionListeners, and it would be better to check if the username is not empty, then pass the actual work off to another thread, for instance with a SwingWorker, but for your purposes I suspect it will be alright to not worry about that.}

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