Lambda表达式内的组合谓词

Question

This is a two part question.

I have a boolean field and several String[] fields and I need to evaluate predicates for each one.

The following code gets interfaces for each device. I then want to evaluate those interfaces based on the predicates.

1. Is there a more efficient way to do it?

2. .filter(predicates.stream().reduce(Predicate::or) gives this error: that I'm unsure how to resolve.

     parentReference.getDevices().stream().parallel().filter(ASA_PREDICATE).forEach((device) -> { List<Predicate<? super TufinInterface>> predicates = new ArrayList(); if (iName != null) { Predicate< ? super TufinInterface> iNameFilter = myInterface -> Arrays.stream(iName) .allMatch(input -> myInterface.getName().toLowerCase().contains(input.toLowerCase())); predicates.add(iNameFilter); } if (ipLow != null) { Predicate< ? super TufinInterface> ipLowFilter = myInterface -> Arrays.stream(ipLow) .allMatch(input -> myInterface.getName().toLowerCase().contains(input.toLowerCase())); predicates.add(ipLowFilter); } if (ip != null) { Predicate< ? super TufinInterface> ipFilter = myInterface -> Arrays.stream(ip) .allMatch(input -> myInterface.getName().toLowerCase().contains(input.toLowerCase())); predicates.add(ipFilter); } if (zone != null) { Predicate< ? super TufinInterface> zoneFilter = myInterface -> Arrays.stream(zone) .allMatch(input -> myInterface.getName().toLowerCase().contains(input.toLowerCase())); predicates.add(zoneFilter); } try { ArrayList<TufinInterface> tufinInterfaces = Tufin.GET_INTERFACES(parentReference.user, parentReference.password, parentReference.hostName, device) .stream() .filter(predicates.stream().reduce(Predicate::or) .orElse(t->true)).parallel().collect(Collectors.toCollection(ArrayList<TufinInterface>::new)); interfaces.addAll(tufinInterfaces); } catch (IOException | NoSuchAlgorithmException | KeyManagementException | JSONException | Tufin.IncompatibleDeviceException ex) { Logger.getLogger(InterfaceCommand.class.getName()).log(Level.SEVERE, null, ex); } }); 

Answer 1

Stream has a function called anyMatch that can clean up your filter a bit.

ArrayList<TufinInterface> tufinInterfaces = Tufin.GET_INTERFACES(parentReference.user, parentReference.password, parentReference.hostName, device)
                .stream()
                .filter(s -> predicates.stream().anyMatch(pred -> pred.test(s)))
                .collect(Collectors.toList());