背景资料

我有以下课程:

保险

public class Insurance {
    ...
}

顾客

public class Customer {
    private List<Insurance> insurances;

    public List<Insurance> getInsurances() {
        return insurances;
    }
    ...
}

CustomerRegistry

public class CustomerRegistry {
    private List<Customer> customers;
    ...
}

以及这个帮助方法,它将a减少List<Predicate<T>>为单个Predicate<T>:

public Predicate<T> reducePredicates(List<Predicate<T>> predicates) {
    return predicates.stream()
                     .reduce(Predicate::and)
                     .orElse(p -> true);
}

问题

我想要做的是获得与过滤器列表匹配的保险列表,这些过滤器属于与过滤器列表匹配的客户.如果不清楚,下面的代码将有希望澄清.

方法在CustomerRegistry上面的类中.

public List<Insurance> findInsurances(List<Predicate<Customer>> cusPredicates,
List<Predicate<Insurance>> insPredicates) {

    List<Insurance> matches = new LinkedList<>();
    customers.stream()
             .filter(reducePredicates(cusPredicates)
             .forEach(cus -> cus.getInsurances()
                               .stream()
                               .filter(reducePredicates(insPredicates))
                               .forEach(cus -> matches.add(cus))) …