Limit number of character on every JTextArea line

I have a JTextArea in a JDialog. JDialog uses a GridLayout.

I would like to have 7 digits on each line of the JTextArea (each line will be a 7 int registration number). For user experience reasons, I would like the JTextArea to either add a new line or stop expanding when it reaches 7 characters on a line.

Things that didn't work : - Specifying the number of columns in the JTextArea constructor - matriculesText.setLineWrap(true); and matriculesText.setWrapStyleWord(true);

I'm afraid uploadDialogManager.setHgap(20); might be breaking the code. I'm wondering if the JDialog should rather have a fixed size.

This is how I construct my JDialog :

// initialization
    Dialog uploadParent = null;
    JDialog uploadDialog = new JDialog(uploadParent);
    GridLayout uploadDialogManager = new GridLayout(UPLOAD_DIALOG_ROWS, 
UPLOAD_DIALOG_COLUMNS);

    // uploadDialog properties
    uploadDialog.setSize(new Dimension(UPLOAD_DIALOG_WIDTH, UPLOAD_DIALOG_HEIGHT));
    uploadDialog.setLayout(uploadDialogManager);
    uploadDialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);

    //Set up the horizontal gap value
    uploadDialogManager.setHgap(20);
    //Set up the vertical gap value
    uploadDialogManager.setVgap(20);
    //Set up the layout of the buttons
    //uploadDialogManager.layoutContainer();

    // components initialization
    JLabel exerciceLabel = new JLabel("exercice number : ");
    JComboBox<Integer> exerciceNumbers = new JComboBox<Integer> 
  (EXERCICE_NUMBERS);
    JLabel matriculeLabel = new JLabel("please enter your matricules, one per 
  line : ");
    JTextArea matriculesText = new JTextArea(1, 1);
    JButton confirm = new JButton("confirm");
    JButton cancel = new JButton("cancel");

    matriculesText.setLineWrap(true);
    matriculesText.setWrapStyleWord(true);

I have made another solution that fills my requirements. Instead of going to a new line when 7 characters are reached, I use MATRICULE_REGEX to check if every line contains 7 digits (1\\d{6}). If it doesn't, I reject the JTextArea content.

    private static final String MATRICULE_REGEX = "1\\d{6}(\\n1\\d{6})*";

    Pattern matriculePattern = Pattern.compile(MATRICULE_REGEX);
    Matcher matriculeMatcher = null;
    matriculeMatcher = matriculePattern.matcher(text);
    isValidMatricule = matriculeMatcher.matches();