collections - 确保元素列表按元素中的字段排序

Question

使用Guava可以通过这种方式确保升序:

import com.google.common.collect.Ordering;
import io.predictor.dao.ohlcv.OhlcvHm;
import static java.util.stream.Collectors.toList;

assertThat("Ordered by age", Ordering.natural().isOrdered(
    employees.stream().map(Employee::getAge).collect(toList())));

令我感到奇怪的是，Guava(尽管它与 Java lambda 关系密切)并没有为这种情况提供简单的解决方案。当然，我可以编写一些帮助方法并将其包装起来，但也许有人已经在库中完成了它。有最简单的方法吗？像这样的东西:

XLibrary.isOrdered(employees, Employee::getAge);

Answer 1

assertThat("Ordered by age", 
           Ordering.from(Comparator.comparing(Employee::getAge)).isOrdered(list);

或

assertThat("Ordered by age", 
           Ordering.natural().onResultOf(Employee::getAge).isOrdered(list);