将部分数独文本文件加载到2D数组中

Question

I am making a Sudoku game and I have an issue with opening a saved Sudoku file. Let's say I am doing the puzzle, and want to come back to it later, I save the partially completed puzzle to a file, which works. When I go to open it, it does not work.

Here is the code for save (both variables ROWS and COLUMNS are equal to 9):

private void savePuzzle() throws IOException {

    JFileChooser fileChooser = new JFileChooser();
    int returnVal = fileChooser.showDialog(this, "Save");

    BufferedWriter saveFile = null;
    File file;

    // If the user has canceled, no need to continue
    if (returnVal != JFileChooser.APPROVE_OPTION) {
        return;
    }

    file = fileChooser.getSelectedFile();

    saveFile = new BufferedWriter(new FileWriter(file));
    for (int r = 0; r < ROWS; r++) {
        for (int c = 0; c < COLUMNS; c++) {
            saveFile.write(inputBoxes[r][c].getText());
            if (c < ROWS - 1) {
                saveFile.write(",");
            }
        }
        saveFile.write("\n");
    }
    saveFile.close();
}

Here is the action button for save:

saveAction.addActionListener(new ActionListener() {

        public void actionPerformed(ActionEvent evt) {
            try {
                // call method to save puzzle by writing its contents to an external save file
                savePuzzle();
            } catch (IOException ex) {
                System.out.println(ex.toString());
            }
        }
    }); 

Here is the code for open:

private void openPuzzle() throws FileNotFoundException, IllegalArgumentException {

    JFileChooser fileChooser = new JFileChooser();
    int returnVal = fileChooser.showDialog(this, "Open");

    File file = fileChooser.getSelectedFile();
    Scanner readFile = new Scanner(file);

    // If the user has canceled, no need to continue with open process
    if (returnVal != JFileChooser.APPROVE_OPTION) {
        return;
    }

    // Row
    int r = 0;

    // Update squares with data from file
    while (readFile.hasNextLine()) {
        String[] splitLine = readFile.nextLine().split(",");

        // Verify the length of the row
        if (splitLine.length != 9) {
            throw new IllegalArgumentException(String.format("Row length(%d) not correct in %s at row %d",
                    splitLine.length, file, r));
        }

        for (int c = 0; c < 9; c++) {
            // Verify each item in row
            if (splitLine[c].length() != 1 || !(Character.isDigit(splitLine[c].charAt(0)))) {
                throw new IllegalArgumentException(String.format("Invalid token %s in %s at row %d col %d",
                        splitLine[c], file, r, c));
            }
            // Update square
            inputBoxes[r][c].setText(splitLine[c]);
        }
        // Move to next row
        r++;
    }
}

And the open action button:

openAction.addActionListener(new ActionListener() {

        public void actionPerformed(ActionEvent evt) {
            try {
                // call method so that user can open their saved puzzle and populate the grid with its contents
                openPuzzle();
            } catch (FileNotFoundException ex) {
                System.out.println(ex.toString());
            } catch (IllegalArgumentException ex) {
                System.out.println(ex.toString());
            }
        }
    });

I know that the open code is finding empty values in the saved text file if it is a partially completed puzzle, and it is returning those catch statements, but I have no clue how to get it to just keep reading each element on the line (whether it's a number or empty space), and just return what's in the text file to the GUI grid (populate the grid with the corresponding numbers).

The errors I'm getting are either the "Row length %d..." error or the "Invalid token %s..." error. It loads nothing back into the grid when I select the file from the Open function. That's where I'm lost. If the puzzle is complete, and it is saved, then it can be open, because the external text file that contains the puzzle is full, and each element (space) in the file has a number in it, so when it iterates over each number, it does not find any errors or missing numbers. But when a partial file is saved, it cannot be opened back into the grid to start playing it again...

Answer 1

Your representation of a (sample) row is this:

1,2,,7,6,,,,5

But when you split that line on , , you will get:

[1,2,7,6,5]

This is clearly not an array of length 9, so if (splitLine.length != 9) will return false . You must save a non-digit character to the text file that indicates an 'empty' space, or the split function will very rarely return a row of the correct length. It is possible to represent an entire Sodoku board with a single list of 81 characters, the digits 0 through 9 and an 'empty' character, no commas or line breaks needed. The key here is that the empty character is still required to maintain the topology of your data structure.

As a side note this:

if (c < ROWS - 1) {
    saveFile.write(",");
}

Should probable reference COLS instead.

Answer 2

From reading your code it would seem to me that the offending line is:

if (splitLine[c].length() != 1 || !(Character.isDigit(splitLine[c].charAt(0)))) {
            throw new IllegalArgumentException(...

In the function openPuzzle. This is because when saving a partially completed sudoku your file will look like "1,2,,3,,1,6,7,....." Now the empty cells when read in will have a string length of 0. So splitLine[c].length() != 1 will fail. To solve this i would suggest changing the code to be:

if (splitLine[c].length() > 0 || !(Character.isDigit(...

So that zero length characters (unfilled spaces) are accepted when loading it in.