Fetch values from Object using map() operator and apply predicate

Question

Please bear with me for silly question, I am new to Java8. I have to write the following code using lambda and apply the condition on the two attribute. I am able to fetch one and apply predicate on it.

for (EventTypePricingMapping eventTypePricingMapping : eventTypePricingMappings) {
        BigDecimal feePerRevenue = eventTypePricingMapping.getFeePerRevenue();
        if (feePerRevenue != null && feePerRevenue.intValue() < 0) {
            throw ExceptionHelper.badRequest("Fee Per Transaction can't be less than zero");
        }
        if (eventTypePricingMapping.getFeePerReg().intValue() < 0) {
            throw ExceptionHelper.badRequest("Fee Per Transaction can't be less than zero");
        }
    }

In the below code how can i fetch the value of feePerRevenue and apply predicate on it, as i have done for that getfeePerReg in the below code.

boolean isRegFeeInvalid = globalPricingRequests.stream()
                .map(GlobalPricingRequest::getEventTypePricingList)
                .flatMap(List::stream)
                .map(EventTypePricingMapping::getFeePerReg)
                .anyMatch(criteria);

My predicate is like as below :

Predicate<BigDecimal> criteria = value -> value != null && value.signum() < 0;

I have tried the below code as per suggestion but i am not able to fetch both the values in map() in the

boolean isRegFeeInvalid = globalPricingRequests.stream()
                .map(GlobalPricingRequest::getEventTypePricingList)
                .flatMap(List::stream)
                .map(EventTypePricingMapping::getFeePerReg,EventTypePricingMapping::getFeePerReg)
                .anyMatch(verifyFeePerRegAndFeePerRevenue());




private static boolean verifyFeePerRegAndFeePerRevenue(BigDecimal feePerReg, BigDecimal feePerRevenue) {
        Predicate<BigDecimal> criteria = value -> value != null && value.signum() < 0;
        return criteria.test(feePerReg) && criteria.test(feePerRevenue);
    }

How to fetch two values in line map(EventTypePricingMapping::getFeePerReg,EventTypePricingMapping::getFeePerReg) and pass them in anyMatch operator

Answer 1

map

<R> Stream<R> map(Function<? super T,? extends R> mapper)

Returns a stream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

So i will suggest to create two different List, one for feePerReg and another for feePerRevenue

feePerReg

List<BigDecimal> feeperReg =  globalPricingRequests.stream().flatMap(eventPrice->eventPrice.getEventTypePricingList().stream()).map(eventType->eventType.getFeePerReg()).collect(Collectors.toList());

feePerRevenue

List<BigDecimal> feePerRevenue = globalPricingRequests.stream().flatMap(eventPrice->eventPrice.getEventTypePricingList().stream()).map(eventType->eventType.getFeePerRevenue()).collect(Collectors.toList());

Predicate Predicate to check for both lists

Predicate<BigDecimal> criteria = value -> value != null && value.signum() < 0;

verifyFeePerRegAndFeePerRevenue method that takes two List<BigDecimal> as arguments

private static boolean verifyFeePerRegAndFeePerRevenue(List<BigDecimal> feePerReg, List<BigDecimal> feePerRevenue) {
    Predicate<BigDecimal> criteria = value -> value != null && value.signum() < 0;
    return feePerReg.stream().anyMatch(criteria) && feePerRevenue.stream().anyMatch(criteria);
}

Case 2

Instead of two different List, you can have only one list with eventTypePricingMapping and Predicate condition on both feePerReg and feePerRevenue

eventTypePricingMapping

List<EventTypePricingMapping> result = globalPricingRequests.stream().flatMap(eventPrice->eventPrice.getEventTypePricingList().stream()).collect(Collectors.toList());

Predicate Predicate to check for both

Predicate<EventTypePricingMapping> criteria = value -> value.getFeePerRevenue() != null && value.getFeePerReg()!= null && value.getFeePerRevenue() < 0 && value.getFeePerReg < 0;

verifyFeePerRegAndFeePerRevenue method takes List<EventTypePricingMapping> apply Predicate on list

private static boolean verifyFeePerRegAndFeePerRevenue(List<EventTypePricingMapping> price) {
    Predicate<EventTypePricingMapping> criteria = value -> value.getFeePerRevenue() != null && value.getFeePerReg()!= null && value.getFeePerRevenue() < 0 && value.getFeePerReg < 0;
    return price.stream().anyMatch(criteria);
}