PrintWriter does not write to specified file

Question

I have a program that has to read in a file calculate multiple things such as how many vowels in the file etc. For testing purposes I have just been printing the results to the console however I need it to be printed to a separate file so I am using Print Writer. I will include my whole code, so you can see exactly what it is doing.

   //Variables
    int vowels = 0, digits = 0, spaces = 0, upperCase = 0, lowerCase = 0;
    char ch;

    // Creates File Chooser and Scans Selected file.
    Scanner in = null;
    File selectedFile = null;
    JFileChooser chooser = new JFileChooser("E:/OOSD/src/textAnalyser");
    if (chooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
        selectedFile = chooser.getSelectedFile();
        in = new Scanner(selectedFile);
    }

    //Loops through the file until it has counted everything. 
    while (in.hasNext()) {
        //Gets the next line from the input
        String line = in.nextLine();
        // loop goes on till it has no next line.
        for (int i = 0; i < line.length(); i++) {   
            ch = line.charAt(i);
    if (ch == 'a' || ch == 'A' || ch == 'e' || ch == 'E' || ch == 'i'
    || ch == 'I' || ch == 'o' || ch == 'O' || ch == 'u' || ch == 'U') {
                vowels++;
            } else if (Character.isDigit(ch)) {
                digits++;
            } else if (Character.isWhitespace(ch)) {
                spaces++;
            } else if (Character.isUpperCase(ch)) {
                upperCase++;
            } else if (Character.isLowerCase(ch)) {
                lowerCase++;
            }
        }
    }//Ends While Loop.

    PrintWriter writer = new PrintWriter("Output.txt", "UTF-8");
    writer.println("Vowels: " + vowels);
    writer.println("Digits : " + digits);
    writer.println("Spaces : " + spaces);
    writer.println("Capital Letters : " + upperCase);
    writer.println("LoweCase : " + lowerCase);
    writer.close();

If you could tell me why it won't print to the output file specified that would be great thanks :) sorry that it is a pretty long question.

Check out this post: http://stackoverflow.com/questions/11496700/how-to-use-printwriter-and-file-classes-in-java — monsocla, Apr 08 '15 at 13:00
It should write to the file specified. If it doesn't you may be doing something wrong. Is an error message produced? Are you sure you are looking for the file in the right directory? — Peter Lawrey, Apr 08 '15 at 13:00

score 2 · Answer 1 · answered Apr 08 '15 at 13:11

2

Your PrintWriter has autoflush disabled. Either enable it in the constructor, or flush manually before the writer is closed. And since you read lines, you should use in.hasNextLine() rather than in.hasNext().

answered Apr 08 '15 at 13:11

1

To expand on this - the PrintWriter by default will store things up in memory and not actually flush (i.e. write) them to the file on disk until you explicitly tell it to by calling `writer.flush()`. Enabling auto flush means the writer will flush/write to the file as you go without the need to an explicit call. – Paolo Apr 08 '15 at 13:39

score 0 · Accepted Answer · answered Apr 08 '15 at 13:40

for your program to work you need to flush your PrintWriter before closing it.

    PrintWriter writer = new PrintWriter("C:/Users/r7h8/Output.txt", "UTF-8");
    writer.println("Vowels: " + vowels);
    writer.println("Digits : " + digits);
    writer.println("Spaces : " + spaces);
    writer.println("Capital Letters : " + upperCase);
    writer.println("LoweCase : " + lowerCase);
    writer.flush();
    writer.close();

When you flush it, the content is written to the file.

Best regards.

PrintWriter does not write to specified file

2 Answers2