The document discusses enhancements and new features in Java from versions 9 to 13, including local variable type inference with 'var', the Stream API methods like takeWhile and dropWhile, and improvements in switch expressions. It covers practical examples of using these features and poses quizzes related to Java functionalities. The presentation also highlights the importance of learning new features and sharing knowledge among colleagues.

1. 1
Блок Т
What did you miss in Java
from 9 to 13?

2. 2
How I am?
SOKOVETS ARTEM
Head of AutomationQA @SberTech
#java, #kotlin #flutter
asokovets@gmail.com/@SokovetsArtem

3. 3
Agenda
1. Enhancements
2. CodeOne Pitch
3. Java Quiz

4. 4
Local Variable Type Inference => var (JDK 10)
New reserved word var for defining local variables,
instead of explicit type specification
var techTalk = "Java 9 to 13?"; //var => String
var chars = techTalk.toCharArray()//var=>char[]
var mike = new Person("Mike", 47);//var=>Person
var hash = mike.hashCode(); //var => int
possible if the concrete type for a local variable can be
determined by the compiler using the definition on the
right side of the assignment.

5. 5
Local Variable Type Inference => var (JDK 10)
Especially useful in the context of generics spelling
abbreviations:
ArrayList<String> var names = new ArrayList<String>();
var names = new ArrayList<String>();
names.add("Tim"); names.add("Tom");
// var => ArrayList<String> names
// var => Map<String, Long>
Map<String, Long> var personage =
Map.of("Tim", 47L, "Tom", 12L, "Michael", 47L);

6. 6
Local Variable Type Inference => var (JDK 10)
var is not suitable for Lambda-expressions
Thus no conversion into var is possible, but leads to the error
message >>
“Lambda expression needs an explicit target-type”.
To avoid this mistake, the following cast should be
inserted:
var isAdultVar =
(Predicate<Map.Entry<String, Long>>)
entry -> entry.getValue() >= 18;

7. 7
Stream API in JDK9
takeWhile(...) dropWhile(...)
ofNullable(...)
takeWhile(Predicate<T>) – processes elements as long as the
condition is met

8. 8
Take While Scenario

9. 9
TakeWhile
takeWhile(Predicate<T>) – processes elements as long as the
condition is met
Stream<String> productQuality = Stream.of("Good",
"Good", "Good", "Bad", "Good");
productQuality.takeWhile(pd ->
pd.contains("Good")).forEach(out::println);

10. 10
Stream API in JDK9
dropWhile(Predicate<T>) – skips/drops elements as long as
the condition is met
takeWhile(...) dropWhile(...)
ofNullable(...)

11. 11
DropWhile
dropWhile(Predicate<T>) – skips/drops elements as long as
the condition is met
IntStream marks = IntStream.of(2,3,5,5);
marks.dropWhile(it -> it < 4)
.forEach(out::println);
>> 5
>> 5

12. 12
Combination of the two methods for extracting data
Stream<String> words = Stream.of(
"ab", "BLA", "Xy", "<START>","WELCOME", "TO",
”SBERBANK", ”TECH TALKS","<END>", "x", "y", "z");
Stream<String> extracted = words
.dropWhile(str ->!str.startsWith("<START>"))
.skip(1)
.takeWhile(str -> !str.startsWith("<END>"));
>> WELCOME
>> TO
>> SBERBANK
>> TECH TALKS

13. 13
Stream API in JDK9
ofNullable(T) - method returns a sequential Stream containing
a single element if this stream is non-null otherwise method
returns an empty Stream.
takeWhile(...) dropWhile(...)
ofNullable(...)

14. 14
OfNullable
List<String> collection = Arrays.asList("A", "B", "C");
Map<String, Integer> map = new HashMap<>() {
{ put("A", 10); put("C", 30);}
};
private Stream<Integer> getStream() {
return collection.stream().flatMap(s -> {
Integer temp = map.get(s);
return temp != null ? Stream.of(temp) :
Stream.empty();
});
}
private Stream<Integer> getStreamWithOfNullable() {
return collection.stream().flatMap(s ->
Stream.ofNullable(map.get(s)));
}
JDK8
JDK10

15. 15
Optional<T> JDK 9 (ifPresentOrElse)

16. 16
Optional<T> JDK 9 (or)

17. 17
Optional<T> JDK 9 (stream)

18. 18
Why ifPresentOrElse(…) ?

19. 19
Why ifPresentOrElse(…) ?

20. 20
Why or(…) ?

21. 21
Why or(…) ?

22. 22
java.util.Optional<T> (JDK 11)

23. 23
Collection Factory Methods

24. 24
The Class LocalDate

25. 25
The Class LocalDate

26. 26
Enhancements in java.lang.String: lines()

27. 27
Enhancements in java.lang.String: repeat()

28. 28
Utility-class java.nio.file.Files

29. 29
Switch Expressions: Retrospect
DayOfWeek day = DayOfWeek.FRIDAY;
int numOfLetters = -1;
switch (day)
{
case MONDAY:
case FRIDAY:
case SUNDAY:
numOfLetters = 6;
break;
case TUESDAY:
numOfLetters = 7;
break;
case THURSDAY:
case SATURDAY:
numOfLetters = 8;
break;
case WEDNESDAY:
numOfLetters = 9;
break;
}

30. 30
Switch Expressions: Retrospect
DayOfWeek day = DayOfWeek.FRIDAY;
int numLetters = -1;
switch(day)
{
case MONDAY, FRIDAY, SUNDAY -> numLetters = 6;
case TUESDAY -> numLetters = 7;
case THURSDAY, SATURDAY -> numLetters = 8;
case WEDNESDAY -> numLetters = 9;
}
Mapping of weekdays to their length… elegantly with Java
12 / 13:

31. 31
Switch Expressions: Retrospect
Mapping of weekdays to their length… elegantly with Java
12 / 13:
DayOfWeek day = DayOfWeek.FRIDAY;
int numLetters = switch (day)
{
case MONDAY, FRIDAY, SUNDAY -> 6;
case TUESDAY -> 7;
case THURSDAY, SATURDAY -> 8;
case WEDNESDAY -> 9;
};
Return
Value

32. 32
Text Blocks (JDK 13)

33. 33
What else?
• HTTP/2 API Intro
• Multi-Threading and the Class CompletableFuture<T>
• Java Module

34. 34
CodeOne Pitch
• Kotlin is growing up
• RPA – new way in automation testing
• Use Method Handler instead of Reflection API
• Test Engine for flexible test framework in Junit 5
• Quantum computers are coming

35. 35
Java Quiz #1
Which can fill in the blank?
interface TheInterface {
____ int method() { return 1; } }
A.public
B.protected
C.no modifier
D.private
E.None of the above

36. 36
Java Quiz #2
What is the output?
var a = 1; var b = a;
String c = b; System.out.println(c);
A.a does not compile
B.b does not compile
C.c does not compile
D.1
E.None of the above

37. 37
Takeaways
• Try to learn new features in Java -> Kotlin
• Share your knowledge to colleagues