java - 在java中组合比较器

Question

我有 2 个比较器:

Comparator<? super MyClass> COMPARATOR_BY_PRIORITY =
        Comparator.nullsFirst(
                Comparator.comparing(c -> c.isEmpty() ? null : -c.getPriority())
        );

Comparator<? super MyClass> COMPARATOR_BY_PRICE =
        Comparator.nullsFirst(
                Comparator.comparing(c -> c.isEmpty() ? null : c.getPrice())
        );

我想将它们组合起来，以便使用组合比较器可以按优先级对项目进行第一排序，并按价格对具有相同优先级的项目进行排序。如何创建组合比较器？

我正在尝试类似的东西:

Comparator<? super MyClass> COMBINED_COMPARATOR =
    COMPARATOR_BY_PRIORITY.thenComparing(COMPARATOR_BY_FARE);

Answer 1

正如@tobias_k 所指出的，没有 ? super :

Comparator<MyClass> COMPARATOR_BY_PRIORITY =
        Comparator.nullsFirst(
                Comparator.comparing(c -> c.isEmpty() ? null : -c.getPriority())
        );

Comparator<MyClass> COMPARATOR_BY_PRICE =
        Comparator.nullsFirst(
                Comparator.comparing(c -> c.isEmpty() ? null : c.getPrice())
        );

Comparator<MyClass> COMBINED_COMPARATOR =
    COMPARATOR_BY_PRIORITY.thenComparing(COMPARATOR_BY_FARE);