I've done this before once, I'm trying to replicate what I did so far and this is what I've got:

    try {
        BufferedWriter writer = new BufferedWriter(new FileWriter("file.P", true));
        System.out.println("entered");
        if (!(newUserName.isEmpty()) || (newUserPass.isEmpty())){
            writer.newLine();
            writer.write("hellotest123");
            writer.close();
        }

It seems to find file.P, which is just a txt file, but it doesn't seem to append anything onto it? It enters the code and passes the IF statement fine, but nothing is appended to the text file? I'm slightly stuck!