The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
forEach
aggregate operation differs from the enhanced
for
statement
or iterators.double average = roster .stream() .filter(p -> p.getGender() == Person.Sex.MALE) .mapToInt(Person::getAge) .average() .getAsDouble();
p -> p.getGender() == Person.Sex.MALE
is an example of what?
Person::getAge
is an example of what?
Stream.reduce
method
and the Stream.collect
method.
List
, would Stream.reduce
or
Stream.collect
be the
most appropriate operation to use?
for
statement as a
pipeline with lambda expressions. Hint: Use the
filter
intermediate operation and the forEach
terminal
operation.
for (Person p : roster) { if (p.getGender() == Person.Sex.MALE) { System.out.println(p.getName()); } }
for
loops. Hint: Make a pipeline that invokes the filter
, sorted
, and
collect
operations, in that order.
List<Album> favs = new ArrayList<>(); for (Album a : albums) { boolean hasFavorite = false; for (Track t : a.tracks) { if (t.rating >= 4) { hasFavorite = true; break; } } if (hasFavorite) favs.add(a); } Collections.sort(favs, new Comparator<Album>() { public int compare(Album a1, Album a2) { return a1.name.compareTo(a2.name); }});