Learn the Concepts Behind Those 10 Java Challenges and Eliminate Stressful Bugs
Abstract: Bugs are a daily stress in our work as Java developers. Those pesky bugs hide behind important Java concepts; there is no way out of this. But can we have fun hunting them? How about solving a series of Java puzzles and challenges as a way to learn concepts and save a lot of time finding those tricky bugs? In this session, attendees solve fun Java challenges and gain a clear understanding of what causes the most stressful Java bugs—and have fun eliminating them from your projects. Speaker: Rafael Chinelato Del Nero, Systems Analyst, NoBugsProject (Oracle Certified) Rafael Del Nero, the creator of NoBugsProject, is the author of "No Bugs, No Stress - Create a Life-Changing Software Without Destroying Your Life." Rafael believes there are many techniques involved in creating high-quality software that developers are often unaware of. His life's purpose is to help Java developers use best programming practices to code quality software for stress-free projects with fewer bugs. Barry Evans, Senior Applications Consultant, Dublin JUG / Version 1 (Oracle Certified) Barry is a seasoned web application engineer with over 10 years experience developing enterprise applications predominantly in the financial sector. He has been using Java SE, Spring, and ORM to build middleware for RIA apps written in Adobe Flex & AS3, Angular JS, and HTML 5. Recently OCP Java SE 8 certified, he is keen to increase his knowledge of Java EE and is working towards the OCMJEA certification. Barry is also interested in meeting other JUG leaders, finding out what brings Java developers together, and he wants to help the Dublin JUG in Ireland grow by getting involved with the global Java community.
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Learn the Concepts Behind Those 10 Java Challenges and Eliminate Stressful Bugs
- 1. Learn the concepts behind 10 Java Challenges and Eliminate Stressful Bugs!
- 2. Who we are... Rafael Del Nero - Made in Brazil - Creator of nobugsproject.com - #JavaChallenges - Author of "No Bugs, No Stress - Create a Life Changing Software Without Destroying Your Life” book - He helps Java developers use best programming practices to code quality software for stress-free projects with fewer bugs. - Shares Barry’s daughters birthday (19/09) Barry Evans - Made in (N) Ireland - Java == since 2007 - 💚s Clean Code & TDD - 💔s Bugs & Untested Code - Java 8 SE OCP Certified - 2nd JavaOne - version1.com - DubJUG.org
- 3. Topics we will cover 1. Generics 2. Strings 3. Crazy Syntax 4. Threads 5. equals & hashCode 6. Sorting & Comparable 7. 𝝺 -> Lambdas 8. Method Overloading 9. Streams 10. Polymorphism
- 4. A) It will not compile B) Maggie C) RuntimeException at line 32 D) Homer Generics #1
- 5. A) 2367 B) 2357 C) 2368 D) 1457 Strings #2
- 6. A) It won’t compile at line 12, 17 and 19 B) It won’t compile at line 11, 27 and 30 C) It won’t compile at line 5, 24 and 30 D) It will compile Crazy Syntax #3
- 7. A) first B) third C) last D) Indeterminate Threads #4
- 8. A) 1> 2> 3> 4> 5> B) Indeterminate C) 4> 2> 5> D) 5> 4> 3> 2> 1> equals & hashCode #5
- 9. A) Bart Homer Lisa Maggie Marge B) Marge Maggie Lisa Homer Bart C) Maggie Bart Lisa Marge Homer D) Indeterminate Sorting & Comparable #6
- 10. A) It won’t compile at line 9. B) It won’t compile at line 24. C) BAMM!!POHHHH!!! D) It won’t compile at line 20 𝝺 -> Lambdas #7
- 11. A) befe B) bfce C) efce D) aecf 1 - Widening 2 - Boxing 3 - Boxing+varargs Method Overloading #8
- 12. A) 31 B) Prints to ∞... C) Prints nothing D) java.util.NoSuchElementException Streams #9
- 13. A) Spider Pig! Eat my shorts! I love Sax! B) Spider Pig! Simpson! I love Sax! C) Spider Pig! Eat my shorts! Simpson! D) Simpson! Simpson! Simpson! Polymorphism #10
- 14. Topics we covered 1. Generics 2. Strings 3. Crazy Syntax 4. Threads 5. equals & hashCode 6. Sorting & Comparable 7. 𝝺 -> Lambdas 8. Method Overloading 9. Streams 10. Polymorphism
Editor's Notes
- Generic Type Parameter Generic Type parameter scope Class/Method Explain the generic type in the class Explain the generic type in the method
- String pool Immutable String == != equals TODO Align all ternary returns – e.g. ? “3” : “4”
- For structure Variable names Generic types declarations
- Thread execution order is indeterminate Thread priority is only a preference Daemon threads will not keep the jvm alive No output is possible System.exit(0) | Runtime.exit(0) or All threads that are not daemon threads have died
- HashMap uses hashcode, then equals to find unique entries Hashcode will be used 1st time, then equals LinkedHashMap will guarantee the iteration order cheaper than TreeMap Map.forEach uses BiConsumer (accept) java 8 feature
- TreeSet requires Comparable<?> interface compareTo provides reverse alpha order Equals never used with TreeSet ArrayList.forEach uses Consumer (accept) java 8 feature Or method reference 8 calls Homer,Homer Homer,Marge Homer,Lisa Marge,Lisa Lisa,Bart Homer,Bart Lisa,Maggie Marge,Maggie
- Functional Interface Default methods Lambda syntax
- Widening Boxing Varargs TODO - line up the var parameter names
- Streams intermediate operations Map/Filter Lazy evaluation Stream terminal operation .min Comparator<?> Optional.ifPresent Consumer<?> Stream could be empty Stream.iterate Infinite stream Use limit to bound
- Polymorphism Access modifiers Method overloading Virtual Method Invocation Object reference is irrelevant