Function<Integer, Integer> square = x -> x * x;
Stream<Integer> numbers = Stream.of(1, 2, 3, 4, 5);
int sum = numbers.filter(n -> n % 2 == 0)
.map(n -> n * 2)
.sum().intValue();
List<Student> students = Arrays.asList(
);
public class Student {
private String name;
private int age;
private String gender;
private int score;
}
OptionalDouble averageScore = students.stream()
.mapToInt(Student::getScore)
.average();
