[Solved] Extracting objects from a list by quantity [closed]

by


If you are using java-8 or later then

List<Drink> list = new ArrayList<>();
list.add(new Drink("coke", 30));
list.add(new Drink("fanta", 10));
list.add(new Drink("coke", 5));
list.add(new Drink("sprite", 1));
list.add(new Drink("coke", 10));
Map<String, Integer> map = list.stream()
    .collect(Collectors.groupingBy(Drink::getName, 
                 Collectors.summingInt(Drink::getAmount)));
System.out.println(map);

output
{sprite=1, coke=45, fanta=10}

Collection<Drink> c = 
       list.stream().collect(Collectors.groupingBy(Drink::getName,
            Collectors.collectingAndThen(
                Collectors.reducing((Drink a, Drink b) -> {
                   a.setAmount(a.getAmount() + b.getAmount());
                   return a;
            }), Optional::get))).values();

2

solved Extracting objects from a list by quantity [closed]