Bugs are a daily cause of stress in our work as Java developers. Those pesky things can hide behind core concepts in Java 9 and 10—there is no way out of this. If we don’t keep up to date with new Java versions, bugs will take over our projects. But can we have fun hunting them? You bet! How about solving a series of Java puzzles as a way to master concepts and save a lot of time finding those tricky bugs? In this session, attendees can help the bug hunters solve fun Java challenges, gain a clear understanding of what causes the most-stressful bugs—and have fun eliminating them from projects.

1. Master the Concepts Behind the Java 10
Challenges and Eliminate Stressful Bugs

2. What we will do together...
Learn 10 recently released Java core concepts
by solving fun challenges

3. Lets learn together…
9 10

4. Topics we will see
1. Interface
2. Optional
3. Reactive Streams
4. Try with resources
5. Take and drop while

5. Get to know me...
Rafael Del Nero
- Made in Brazil
- Java Champion
- Quiz master in Oracle Dev Gym
- Creator of the Java Challengers series in Java World
- Creator of nobugsproject.com
- Author of "No Bugs, No Stress - Create a Life Changing
Software Without Destroying Your Life” book.

6. Interface #1
A) LukeSFSYoda
B) LukeXYoda
C) It won’t compile
D) SLukeFSYoda
Not a method override
String delimiter

7. Interface #1
A) LukeSFSYoda
B) LukeXYoda
C) It won’t compile
D) SLukeFSYoda
Can’t override a private method
private methods on interfaces
Default methods

8. Optional #2
A) keyMakerVirus2theOneTRINITY
B) keyMakerVirusArchitect2theOneTRINITY
C) Virus1theOneTRINITY
D) keyMakerVirus1theOne

9. Optional #2
A) keyMakerVirus2theOneTRINITY
B) keyMakerVirusArchitect2theOneTRINITY
C) Virus1theOneTRINITY
D) keyMakerVirus1theOne
Method is invoked
Method is not invoked
String will be lost

10. Optional #2
A) keyMakerVirus2theOneTRINITY
B) keyMakerVirusArchitect2theOneTRINITY
C) Virus1theOneTRINITY
D) keyMakerVirus1theOne
orElse
orElseGet
or

11. Reactive Streams #3
A) Homer Barney Lenny
Moe, get the shotgun
B) Homer No beer.
Moe, get the shotgun
C) It will be a random result
D) Homer Barney Lenny
and StackOverflowError will be thrown
Asynchronous process

12. Reactive Streams #3
A) Homer Barney Lenny
Moe, get the shotgun
B) Homer No beer.
Moe, get the shotgun
C) It will be a random result
D) Homer Barney Lenny
and StackOverflowError will be thrown
Can’t invoke request method with <= 0

13. Reactive Streams #3
A) Homer Barney Lenny
Moe, get the shotgun
B) Homer No beer.
Moe, get the shotgun
C) It will be a random result
D) Homer Barney Lenny
and StackOverflowError will be thrown
Asynchronous process
++ operator
request method has to be
invoked with a positive number

14. Try with resources #4
A) IOException will be thrown
B) >#?#1
C) >>#?#2
D) >#? then IOException will be thrown
Java 9

15. Try with resources #4
A) IOException will be thrown
B) >#?#1
C) >>#?#2
D) >#? then IOException will be thrown
Closable can be passed from outside since
Java 9
Close method is invoked after try block is
executed
No need to use finally to close resources

16. Take and drop while #5
A) 76578
B) 78657
C) 786578
D) 7 and random values

17. Take and drop while #5
A) 76578
B) 78657
C) 786578
D) 7 and random values
// break
Set is an unordered array

18. Take and drop while #5
A) 76578
B) 78657
C) 786578
D) 7 and random values
Take and Drop while will break when the
condition is false
Set interface has unordered elements
Stream.flatMap()

19. Topics we covered
1. Interface
2. Optional
3. Reactive Streams
4. Try with resources
5. Take and drop while

20. To solve more challenges, go to:
nobugsproject.com
JavaDevGym
@rafaDelNero