Java 8 Bootcamp
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This document provides information about a Java 8 Bootcamp training conducted by Mohamed Ben Hassine. It outlines the key topics that will be covered in the training including an introduction to lambda expressions, Java 8 Stream API, new date and time API, Nashorn JavaScript engine, and other Java 8 features. It also provides a brief history of Java releases and versions. The training will use an example project of building an employee management application to demonstrate and apply the Java 8 concepts over the course.
Java 8 Bootcamp
- 1. Mohamed Ben Hassine Java / JEE Technical Lead Trainer [email protected] (+216) 52 633 220 www.linkedin.com/in/mohamedbnhassine Java 8 Bootcamp
- 2. Java 8 Bootcamp What you will Learn • Get Started • Lambda Expressions • Java 8 Stream API • New Date and Time API • Nashorn: New JavaScript Engine • Miscellaneous
- 4. History of Java releases 4 1995 JDKIntroduction January1996 JDK1.0 “OAK”JDK1.0 December1998 J2SE1.2 FoundationofJCJ Swing,Collections February2002 J2SE1.4 Assert,JAXP,IPv6 RegularExpressions February 1997 JDK 1.1 Java Beans, RMI , JDBC, JIT May 2000 J2SE 1.3 HotSpot JVM , JNDI, Java Debugger September 2004 J2SE 5.0 Generics, Metadata, Concurrency, Static Import September 2006 Java SE 6 Java Compiler API ,Support JDBC 4.0 , JVM improvements July 2011 Java SE 7 Try-with-Resources Strings in switch New IO API , Dynamic languages March 2015 Java SE 8 Project Lambda Streams API , Functional Interfaces ,Nashorn Engine ,New Date Time API , Annotations on Type 2017 Java SE 9 Jshell Java REPL , Support HTTP 2.0 , G1 default Garbage Collector Get Started
- 5. Why Java 8 Now ? 5 Get Started Revolution in Processing power Parallel multicores architectures Big Data Applications Code behavior Code as data Functional programming Support Enhance core librairies Interface unlocking (concrete methods ) Backward compatibility Java / Javascript JavaScript made great in Java 8
- 6. Install and configure Java 8 6 Get Started
- 7. Project Based Course 7 Get Started Employee management Throughout the whole course , we will develop a java console app which offers suck key features : Add manage employee Manage employees personal details , salaries and bonus Search employee by predefined criteria
- 8. Lambda Expressions First Lambda Expression Comparator<Employee> compLambda = ( emp1, emp2) -> { int i = Integer.compare(emp1.getAge(), emp2.getAge()); if (i != 0) { return i; } else { i = Double.compare(emp1.getSalary(), emp2.getSalary()); if (i != 0) return i; } return i; }; Collections.sort(persons, compLambda); Much Easier ! persons.sort(Comparator.comparing(Employee::getAge).thenComparing(Employee::getSalary)); Don’t worry about this code for now. This Course will explain what it does and how you can develop similar code!
- 9. Lambda Expressions Why Lambda Expression Using anonymous classes for code behavior parameterization is verbose Programmers struggle with anonymous classes. (confusion “this”, no access to non-final local variables) Convenient for new streams library persons.forEach(emp -> emp.setSalary(3000)); Solution : Lambda let you represent a behavior or pass code in a concise way. Another way to write anonymous classes Comparator<Employee> compLambda = ( emp1, emp2) -> { return emp1.getJobTitle().compareTo(emp2.getJobTitle()); } Lambda Parameters Arrow Lambda Body
- 10. Lambda Expressions How to Write Lambda Expression The simple way More than One line of code Runnable r = () -> { for (int i = 0; i < 2016; i++) { System.out.println("Hello to your Java SE 8 Bootcamp 2016 !"); } }; More than One Argument Comparator<Employee> compLambda = (Employee emp1, Employee emp2) -> { return emp1.getJobTitle().compareTo(emp2.getJobTitle()); } ; FileFilter filter = (File file) -> file.getName().endsWith("class");
- 11. Lambda Expressions So what is exactly Lambda Expression ? Everything in Java has a type so what for Lambda ? : Lambda Expression is Functional Interface ( new Java 8 concept , Interface with one abstract Method..example Runnable , Comparator interfaces known prior to Java SE8 as Single Abstract Method Interface). Where to use A Lambda Expression ? In each case it could be assigned to a variable of Type Functional Interface Runnable r = () -> System.out.println("Hello to your Java SE 8 Bootcamp 2016 !"); ; Lambda Expression
- 12. Lambda Expressions Functional Interface An Interface with only one abstract method Example : public interface Runnable { public abstract void run(); } @FunctionalInterface public interface SimpleInterface { public void doSomeJob() ; } Define Java SE8 Functional Interface
- 13. Lambda Expressions Predefined Functional Interface in JAVA SE8 New Java Package : java.util.function Divided into 4 categories : Supplier Consumer Predicate /** @since 1.8 */ @FunctionalInterface public interface Supplier<T> { /** * Gets a result. * * @return a result */ T get(); } Function /** @since 1.8 */ @FunctionalInterface public interface Consumer<T> { /** * @param t the input argument */ void accept(T t); } /** @since 1.8 */ @FunctionalInterface public interface Predicate<T> { /** * Evaluates this predicate on the given argument. */ boolean test(T t); } /** @since 1.8 */ @FunctionalInterface public interface Function<T, R> { /** * Applies this function to the given argument. */ R apply(T t); }
- 14. Lambda Expressions Method Reference Simply : An other way to write Lambda Expression Comparator<Employee> compLambda = (Employee emp1, Employee emp2) -> { return Double.compare(emp1.getSalary(), emp2.getSalary()) ; } ; Comparator<Employee> compLambdaRef = Comparator.comparing(Employee::getSalary); – Replace (args) -> ClassName.staticMethodName(args) – with ClassName::staticMethodName
- 15. Lambda Expressions So how to process Data with this Lambda ? List<Employee> persons = new ArrayList<>(); persons.add(new Employee("Mohamed", 30, 2500, new Date(), true, "Java / JEE TL")); persons.add(new Employee("Ferdaous", 24, 1900, new Date(), false, "IT Consultant")); // Prior to Java SE 8 for (Employee employee : persons) { System.out.println(employee) ;} Using Lambda Expression // Traverse collection with Lambda Expression persons.forEach(emp -> System.out.println(emp)); // More concise syntax with Method Reference persons.forEach(System.out::println); Where does this method come from ? All interface implementations of Iterable should be refactored !.. Response Next episode ..
- 16. Lambda Expressions Default Method In Java 8 a method can be implemented in an interface. New Java 8 Concept for backward compatibility Allow to add methods to an existing interface long after it has been released without breaking the interface Interface void newMethod() Class implements Compilation Error must implement newMethod Solution to not modify sub class Interface default void newMethod() { Code here…. } Does not break any sub class implementing this Interface Default Method could be overridden in interface implementation
- 17. Lambda Expressions Interface Static Method Similar to default methods except that it is not possible to override them in the implementation classes providing security. Interface static methods are good for providing utility methods. Interface void newMethod() Class implements Compilation Error must implement newMethod Solution to not modify sub class Interface Static void newMethod() { Code here…. } Does not break any sub class implementing this Interface
- 18. JAVA 8 STREAM API
- 19. JAVA 8 Stream API What’s Stream API Coming Soon