package lambdasinaction.chap6;
import static java.util.stream.Collectors.*;
import static lambdasinaction.chap6.Dish.menu;
public class Reducing {
public static void main(String ... args) {
System.out.println("Total calories in menu: " + calculateTotalCalories());
System.out.println("Total calories in menu: " + calculateTotalCaloriesWithMethodReference());
System.out.println("Total calories in menu: " + calculateTotalCaloriesWithoutCollectors());
System.out.println("Total calories in menu: " + calculateTotalCaloriesUsingSum());
}
private static int calculateTotalCalories() {
return menu.stream().collect(reducing(0, Dish::getCalories, (Integer i, Integer j) -> i + j));
}
private static int calculateTotalCaloriesWithMethodReference() {
return menu.stream().collect(reducing(0, Dish::getCalories, Integer::sum));
}
private static int calculateTotalCaloriesWithoutCollectors() {
return menu.stream().map(Dish::getCalories).reduce(Integer::sum).get();
}
private static int calculateTotalCaloriesUsingSum() {
return menu.stream().mapToInt(Dish::getCalories).sum();
}
}