for (int j = 0; j < col; j++)
        {
            gbc.gridy = 1;
            gbc.gridx = j;
            if (j != (col - 1))
                header[j] = new JLabel("I" + (j + 1));
            else
                header[j] = new JLabel("x");
            matrix.add(header[j], gbc);
        }