Examples of filter, map, and reduce in Java 8

exampleOfFilterAndMapInJava8.java

final List<String> integerStrings = Arrays.asList("1", "1", "", "3", null, "5");
final Set<Integer> integers = integerStrings.stream()
        .filter(StringUtils::isNotBlank)
        .map(Integer::valueOf)
        .collect(Collectors.toSet());

moreIntricateExample.java

final Integer id = 5;
final List<Double> valuesForThisId = Arrays.asList(0.54, 1.25, 2.49, null);

final double sumForThisId = identifiedAndIndexedObjectList.stream()
    .filter(x -> id.equals(x.getId()))         // lambda expression
    .map(IdentifiedAndIndexedObject::getIndex) // reference to instance method
    .map(valuesForThisId::get)                 // reference to bound instance method
    .filter(Objects::nonNull)                  // reference to static method
    .reduce(0.0, Double::sum);