将int数组中断为流

Question

我上课了

public class Targets {
    public int[] miniTargets;

    public Targets(int t) {
        miniTargets = new int[t];
        for (int i = 0; i < t; i++) {
            miniTargets[i] = t;
        }
    }
}

而且我想要计算miniTargets我Targets收藏的数量,但我坚持flatMap:

public class App {
    public static void main(String[] args) {
        List<Targets> lst = new ArrayList<Targets>();
        lst.add(new Targets(5));
        lst.add(new Targets(15));
        lst.add(new Targets(25));

        int cnt = (int)lst.stream().map(tg -> tg.miniTargets).flatMap(...).count()
        System.out.println(cnt);
    }
}

Answer 1

如果你想要miniTargets数组的总长度:

int cnt = lst.stream()
             .mapToInt(tg -> tg.miniTargets.length)
             .sum();

如果你想要一个包含miniTargets的IntStream:

IntStream minis = lst.stream()
                     .flatMapToInt (tg -> IntStream.of(tg.miniTargets));