A short introduction to, and practical experiment of, the new features available to the Java craftsman. Java 8 is mostly about new functional programming paradigms. Lambdas, method references and the stream API are powerful and yet sometimes hard to understand concepts. These slides are mainly about describing those features, in a way, that is easy to understand, through, analogies and thought experiements discussions.

1. JAVA8
a short introduction and practical experiment software analyst, 2e systems@joaonunesk
boost your craftsmanship

3. Wat?!

5. { … }

7. @FunctionalInterface

8. Should we verbosely create a basic
implementation of a simple interface?

9. Or should we briefly create a basic
implementation of a simple interface?

10. before
after

11. ( Class :: method )
method references

12. • a static method
• an instance method of an object
• a constructor
Reference….

13. If a method expects a functional interface…
…and if we have a method that looks like the abstract representation of
that functional interface…

14. vs

15. STREAMS

16. filter()
map()
stream()
stream or pipeline input
collect()
stream or pipeline output
filter()
mapToInt()
post stream or pipeline output
getAsDouble()
average()
sum()
anyMatch()
filter()

17. java.util.stream.Stream
collect
map
filter
sorted
anyMatch
findAny findFirst
count
distinct
limit

18. java.util.stream.Collectors
groupingBy
toList
summarizingInt
toSet
partitioningBy
minBy
toMap

22. java.time.LocalDate
java.util.Date and Calendar
vs

23. System.out.println(new Date(2016, 06, 06));
?

24. Thu Jul 06 00:00:00 CEST 3916
time timezone
day month year

25. System.out.println(LocalDate.of(2016, 06, 06));
?

26. 2016-06-06

27. java.time.LocalDateTime
java.time.LocalDate
java.time.LocalTime
java.time.Period
java.time.Instant
java.time.format.DateTimeFormatter
Store
and represent
Parse
and display

29. Drive on the left!

30. Java 8 is much more
optionals, default methods, new tools, javascript engines…

31. design for
failure?

33. the best craft or nothing