Java 8 Features
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My presentation slides in KMS TechCon 2014, an internal technology event at KMS Technology Vietnam company. "Java 8 is one of the most highly anticipated programming language updates in many years. Let me give you an introduction about its new features: Lambda expressions, Method references, Default Methods, Stream API, new JS Engine, new Date/Time API and more..."
![RESOURCES
• http://www.oracle.com/technetwork/java/javase/8-
whats-new-2157071.html
• http://www.techempower.com/blog/2013/03/26/everyt
hing-about-java-8/
• http://www.takipiblog.com/2014/03/18/5-features-in-
java-8-that-will-change-how-you-code/
• http://java.dzone.com/articles/think-twice-using-java-8
• http://www.infoq.com/articles/java-8-vs-scala
• Duke 8 image [http://www.takipiblog.com/]
• Stream image [http://ricianh.blogspot.com/]](https://image.slidesharecdn.com/trungnguyenjava8features-140510201810-phpapp02/85/Java-8-Features-30-320.jpg)
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Java 8 Features
- 1. © 2013 KMS Technology
- 2. JAVA 8 FEATURES TRUNG NGUYEN TECHCON 2014 KMS TECHNOLOGY VIETNAM
- 3. JAVA VERSION HISTORY JDK 1.0 (1996) JDK 1.1 (1997) inner classes JavaBeans, JDBC, RMI, reflection, JIT JDK 1.2 (1998) strictfp keyword Swing API, Collections API J2SE 1.3 (2000) JNDI, JPDA JAVA 8 FEATURES J2SE 1.4 (2002) assert keyword Image IO API, Java Web Start J2SE 5.0 (2004) generics, annotations, enum, varagrs Java SE 6 (2006) Performance improvements Scripting Language, Java Compiler API Java SE 7 (2011) try statement, invokedynamic in JVM String in switch, diamond operation
- 4. JAVA 8 RELEASE (MAR 18, 2014) Java 7 Lambda Expressions Default Methods Stream API New Date/Time APINashorn Java 8 JAVA 8 FEATURES Others
- 5. LAMBDA EXPRESSIONS Java 7 Lambda Expressions Default Methods Stream API New Date/Time APINashorn Java 8 Others JAVA 8 FEATURES
- 6. LAMBDA EXPRESSION JAVA 8 FEATURES Functions in Functional Programming Functions in Java Are arguments, return values from other functions Are variables and be able stored in data structures No new types such as function types Functional Interfaces: are interfaces with exactly one method java.util.function package Consumer, Function, Predicate, Supplier, BiFunction, DoubleConsumer, IntPredicate, LongSupplier, … Lambda Expressions are functions without declaration of access modifier, return value declaration, and name
- 7. LAMBDA EXPRESSION SYNTAX IN JAVA (arguments) -> { body } JAVA 8 FEATURES anonymous inner class lambda expression single-line lambda expression no-parameter lambda expression
- 8. METHOD REFERENCES JAVA 8 FEATURES Lambda expressions only call an existing method Reference to a static method Reference to an instance method of a particular object Reference to an constructor // int Comparator.compare(T t1, T t2) // void Consumer.accept(T t) // T IntFunction.apply(int value)
- 9. WHY LAMBDA EXPRESSIONS IN JAVA? JAVA 8 FEATURES Encourage functional programming Easier to distribute processing of collections over multiple threads More succinct and clear than anonymous inner classes Is Lambda Expression a syntactic-sugar for Anonymous Inner Class?
- 10. HOW LAMBDA EXPRESSIONS WORK? The lambda expression is represented by a new method, and is invoked at run-time using invokedynamic & LambdaMetafactory JAVA 8 FEATURES JVM generation JVM translation Lambda Expression is not a syntactic-sugar for Anonymous Inner Class
- 11. STREAM API Java 7 Lambda Expressions Default Methods Stream API New Date/Time APINashorn Java 8 Others JAVA 8 FEATURES
- 12. DEFINITION OF STREAM JAVA 8 FEATURES Streams are a FP design pattern for processing sequences of elements sequentially or in parallel
- 13. STREAM IN JAVA 8 - EXAMPLE Given a list of photos, I want to find 5 photo names that follow top 3 photos whose average rating is higher than 6, sorted by rating and the total amount of ratings given JAVA 8 FEATURES
- 14. IMPERATIVE STYLE JAVA 8 FEATURES
- 15. STREAM STYLE JAVA 8 FEATURES Coding in Stream API-way Internally iterates through the elements Manipulate the collection data easier and faster Focus on "what" to do instead of "how" to do it The ability to use multiple processor cores for collection processing
- 16. STREAM OPERATIONS JAVA 8 FEATURES Intermediate operations - Lazy processing - Stateless: filter, map, flatMap, peek - Stateful: distinct, sorted, skip - Short-circuiting : limit Terminal operations - Eager processing - forEach, reduce, collect, max, count - Short-circuiting: anyMatch, allMatch, noneMatch, findFirst, findAny - Escape-hatch: iterator, spliterator
- 17. DEFAULT METHODS Java 7 Lambda Expressions Default Methods Stream API New Date/Time APINashorn Java 8 Others JAVA 8 FEATURES
- 18. How to add forEach(Consumer) method into List interface? persons.forEach(person -> personRepo.save(person)); DEFAULT METHODS JAVA 8 FEATURES Default Methods allow to add default implementations to new and/or existing methods of existing interface
- 19. CLASS-EXTENDED IN JAVA 8 JAVA 8 FEATURES Multiple Inheritances behaviors only, no state ‘Diamond Problem’ Solving manually
- 20. CLASS-EXTENDED IN OTHER LANGUAGES Scala Traits (or Ruby Mix-ins) JAVA 8 FEATURES C# Extension Methods
- 21. NEW DATE & TIME API Java 7 Lambda Expressions Default Methods Stream API New Date/Time APINashorn Java 8 Others JAVA 8 FEATURES
- 22. DATE AND TIME API Immutable-value classes Domain-driven design Separation of chronologies JAVA 8 FEATURES Problems of current Date Time API Date, Calendar and SimpleDateFormatter are not thread-safe Poor API design: years start at 1900, months start at 0 No Non-timezone dates/times, durations, periods and intervals New Date and Time API Great but not a Java Standard API Joda-Time
- 23. NEW DATE AND TIME API EXAMPLE JAVA 8 FEATURES LocalDate, LocalTime, LocalDateTime, ZonedDateTime Clock, Duration, Period, ZoneId, ZoneOffset Domain-driven Date and Time Date and Time API classes
- 24. NEW JAVASCRIPT ENGINE (NASHORN) Java 7 Lambda Expressions Default Methods Stream API New Date/Time APINashorn Java 8 Others JAVA 8 FEATURES
- 25. NEW JAVASCRIPT ENGINE (NASHORN) JAVA 8 FEATURES Why Nashorn Engine? Full 100% ECMA262-compliant (edition 5.1) Compiles JS to Java byte-code based on invokedynamic Not match V8 performance, but 2-10x faster than Rhino jjs command line tool Applying Nashorn: Avartar.js and Project Avatar
- 26. OTHER FEATURES Java 7 Lambda Expressions Default Methods Stream API New Date/Time APINashorn Java 8 Others JAVA 8 FEATURES
- 27. OTHER FEATURES JAVA 8 FEATURES Static Methods on Interfaces At beginning, Java allows static fields and static inner types in interface, why not static methods? Yes, it is in Java 8 Optional Class Type Annotations 3rd-parties like Checker Framework use Java Compiler Plug-in and Pluggable Annotations Processing APIs to develop their own analyses
- 28. OTHER FEATURES (CON’T) JAVA 8 FEATURES Repeating Annotations Method Parameter Reflection How to get name of method parameters? java.lang.reflect.Executable.getParameters Compile the source file with the -parameters
- 29. CONCLUSIONS New Features in Java 8 Lambda Expressions Default Methods Stream API New Date/Time APINashorn Others JAVA 8 FEATURES Change the way we write applications
- 30. RESOURCES • http://www.oracle.com/technetwork/java/javase/8- whats-new-2157071.html • http://www.techempower.com/blog/2013/03/26/everyt hing-about-java-8/ • http://www.takipiblog.com/2014/03/18/5-features-in- java-8-that-will-change-how-you-code/ • http://java.dzone.com/articles/think-twice-using-java-8 • http://www.infoq.com/articles/java-8-vs-scala • Duke 8 image [http://www.takipiblog.com/] • Stream image [http://ricianh.blogspot.com/]
- 32. THANK YOU © 2013 KMS Technology