用最大和最小和从（嵌套列表）从使用Java 8的列表列表中获取列表

Question

public class Competitor {
  private final int type;
  private final String name;
  private final int power;

  public Competitor(int type, String name, int power) {
    this.type = type;
    this.name = name;
    this.power = power;
  }

  public int getType() {
    return type;
  }

  public String getName() {
    return name;
  }

  public int getPower() {
    return power;
  }

  @Override
  public String toString() {
    return "Competitor{" + "type=" + type + ", name=" + name + ", power=" + power + "} ";
  }

}

List<List<Competitor>> anotherListOfListCompetitor = new ArrayList<>();
anotherListOfListCompetitor.add(new ArrayList<>(
    Arrays.asList(new Competitor(1, "Cat 00", 93), new Competitor(2, "Dog 18", 40), new Competitor(3, "Pig 90", 90)))); //93 + 40 + 90 = 223

anotherListOfListCompetitor.add(new ArrayList<>(
    Arrays.asList(new Competitor(1, "Cat 23", 20), new Competitor(2, "Dog 30", 68), new Competitor(3, "Pig 78", 32)))); //20 + 68 + 32 = 120

anotherListOfListCompetitor.add(new ArrayList<>(
    Arrays.asList(new Competitor(1, "Cat 10", 11), new Competitor(4, "Cow 99", 90)))); //11 + 90 = 101

现在，我希望获得列表 和值最小的power属性，以及其他列表 和值最大的列表。

我知道减少...

List<Competitor> someListCompetitor = //populate the list

int sumPower = someListCompetitor.stream()
    .map(competitor -> competitor.getPower())
    .reduce(0, (a, b) -> a + b);

但是list > 是否可以用最小的sumpower获得minlistcompettor和最大的sumpower获得minlistcompettor？

List<Competitor> minListCompetitor = anotherListOfListCompetitor
    .stream()... // wich sum power is 101


List<Competitor> maxListCompetitor = anotherListOfListCompetitor
    .stream()... // wich sum power is 223

如何获得这些列表？

Answer 1

您可以使用以下内容：

List<Competitor> minListCompetitor = anotherListOfListCompetitor.stream()
        .min(Comparator.comparingInt(l -> l.stream().mapToInt(Competitor::getPower).sum()))
        .orElse(Collections.emptyList());

List<Competitor> maxListCompetitor = anotherListOfListCompetitor.stream()
        .max(Comparator.comparingInt(l -> l.stream().mapToInt(Competitor::getPower).sum()))
        .orElse(Collections.emptyList());

这将返回列表中的总和.min()/.max()。它使用您提供的代码的简化版本来计算总和。

如果您想在未找到最大值时引发异常，可以使用.orelseThrow()。