Group by two fields then summing BigDecimal

Question

I have a list of taxes:

TaxLine = title:\"New York Tax\", rate:0.20, price:20.00
TaxLine = title:\"New York Tax\", rate:0.20, price:20.00
TaxLine = title:\"Count         


        

Answer 1

Unable to sum up the grouped field can be achieved by Defining a new class called TitleRate inside Taxline class as below.

    class Taxline{
        public static class TitleRate {
            public TitleRate(String title, int taxline) {
                ...
            }

        }

        public TitleRate getTitleRate() {
            return new TitleRate(title, taxline);
        }
    }

To sum the price by grouping title and taxrate, below can be used.

Map> groupedData = people.collect(Collectors.groupingBy(Taxline::getTitleRate));

  List groupedTaxLines = new ArrayList();
  BigDecimal groupedRate = BigDecimal.ZERO;
  for (Map> entry : groupedData.entrySet())
  {
    for(Taxline taxline : entry.getValue()){
        groupedRate = groupedRate.add(taxline.getPrice());
    }
    groupedTaxLines.add(new Taxline(entry.getKey().getTitle, entry.getKey().getRate(), groupedRate));
        groupedRate = BigDecimal.ZERO;
   }