public class CSVWriter {

    public void write_to_csv(ArrayList<Integer> data_array) {

        try (PrintWriter writer = new PrintWriter(new File("C:\\Users\\monik\\Desktop\\test.csv"))) {

            StringBuilder stringBuilder = new StringBuilder();
            DecimalFormat formatter = new DecimalFormat("#.00", DecimalFormatSymbols.getInstance(Locale.ITALY));
            stringBuilder.append("id");
            stringBuilder.append(';');
            stringBuilder.append("x");
            stringBuilder.append(';');
            stringBuilder.append("y");
            stringBuilder.append('\n');

            int index = 0;
            for (int i = 0; i < data_array.size(); i++) {
                index = data_array.get(i);
                stringBuilder.append(i+1);
                stringBuilder.append(';');
                stringBuilder.append(formatter.format(DataLoader.fileNodeCoords.get(index)));
                stringBuilder.append(';');
                stringBuilder.append(formatter.format(DataLoader.fileNodeCoords.get(index+1)));
                stringBuilder.append('\n');
            }

            writer.write(stringBuilder.toString());
            System.out.println("done!");

        } catch (FileNotFoundException e) {
            System.out.println(e.getMessage());
        }
    }
}