Fail to write the reduce method using Stream API

@Getter
public class Dish {
   BigDecimal price;
}

I need to calculate the total price of all ordered dishes, but I fail to write the reduce method. This is a method signature ( argument has a map of Dish and how many times it was ordered ).

So it must be something like this sum of every dish.getPrice * dishQuantaty

    private BigDecimal getOrderTotalPrice(Map<Dish, Integer> dishQuantityMap) {
}

The fail-code I was asked about

  return   dishQuantityMap.entrySet().stream()
        .reduce(BigDecimal.ZERO,
                (dishIntegerEntry) ->
               dishIntegerEntry.getKey().getPrice()
                        .multiply(BigDecimal.valueOf(dishIntegerEntry.getValue())));

Answer

Did you mean something like this:

private BigDecimal getOrderTotalPrice(Map<Dish, Integer> dishQuantityMap) {
  return dishQuantityMap.entrySet().stream()
          .map(d -> d.getKey().getPrice().multiply(new BigDecimal(d.getValue())))
          .reduce(BigDecimal.ZERO, BigDecimal::add);
}