Java 8 - Project Lambda
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Lambda expressions were introduced in Java 8 as a way to write concise code for functional interfaces. They allow passing code as data and reducing boilerplate code. Other Java 8 features include default methods that allow interfaces to have method implementations, and streams that provide a functional way to process collections of data in a declarative way. Parallel streams allow concurrent processing of data. Lambda expressions, default methods, and streams improved Java's support for functional programming.
Java 8 - Project Lambda
- 1. Revolution of Java Java 8 – Project Lambda
- 2. About Me • Java Developer • Technical Teacher • Blogger @kodcu.com
- 3. Java 8 Innovations • Lambda Expressions • Type Inference • Metod References • Collection II • Defender Methods
- 4. Functional Interface ? • An Interface includes only one abstract method called as FunctionalInterface • Lambda expressions are converted to a FI’s implementation in Background
- 5. Functional Interface Examps. • java.lang.Runnable • java.util.concurrent.Callable • java.nio.file.PathMatcher • java.lang.reflect.InvocationHandler • java.beans.PropertyChangeListener • java.awt.event.ActionListener
- 6. Lambda Expressions • Lambda -> (also called Closures), is an expression that reduces vertical boilerplate code. • Concise and Clear code development practice • Interfaces that consist of one more than abstract method, cannot be counterpart of any Lambda expressions. Tip: Exceptions (Defender methods & Object class’ methods)
- 7. Focus to Input & Output Runnable r1=new Runnable() { @Override Input public void run() { Output System.out.println(“Hello Uranus."); } };
- 8. Example
- 9. Lambda Types • 2 type – Single expression // no need “return” • (Integer s) -> ( s*2 ); • |or| (Integer s) -> s*2 ; – Statement Block • (Integer s) -> { return s*2; };
- 10. Type Inference (String s) -> { System.out.println(s); }; // equals (s) -> { System.out.println(s); }; // equals s -> { System.out.println(s); };
- 11. Type Inference (Integer a, Integer b) -> a + b; // equals (a,b) -> (a+b);
- 12. Metod References Runnable r1=new Runnable() { @Override Input public void run() { Output System.out.println(“Hello Uranus."); } };
- 13. Metod References
- 14. Collection II • Collection II is an attachment to existing Collection Framework. • Supports Jquery like chained methods and Underscore.js like Functional Programming Experience.
- 15. Collection II • Existing Collection Framework does not support Concurrent operations in chunked datas. • Cause, existing one applies External Iteration.
- 16. Stream <T> Interface • Sequential and Consumable data structure. • The data cannot be fetch again after consumed. • A Stream object can be obtained any data structure in Collection Framework. • Fo.Exm: LinkedList, ArrayList, HashSet.
- 17. java.util.function Functional Interfaces • Those special Interfaces support general data operations.
- 18. Consumer<T> -> Applying • Consumer gets an input and runs an action. • Does not return any result, only do an action. public void accept(T t);
- 19. Predicate<T> -> Filtering • Predicate gets a conditional code and produce -> true || false • In concise, makes filtering. public boolean test(T t);
- 20. Function<T, R> -> (Consume & Produce); • Gets any type of input object and Produce an output object. public R apply(T t);
- 21. Supplier<T> • Do not get any argument object, only returns instantiation of any object type. public T get();
- 22. Bi? BiPredicate<L, R> Compares two inputted object. BiConsumer<T, U> Consumes two type of objects, and produce no result BiFunction<T, U, R> Gets two input object (T , U) and produce a result (R) . . .
- 23. Parallel Stream • Any parallelizable operations can run concurrently with Parallel stream object. • Parallel Stream object can be obtain with parallelStream() method from any Streamable data structure.
- 24. Lazily & Eagerly Ops. • Some Stream operations can be run Lazly as some Eagerly. Lazy Eager • .filter().map().allMatch(); Lazy Eager • .filter().filter().sorted().forEach();
- 25. Lazily & Eagerly • Lazy operations are evaluated together with first encountered Eager operation. • The goal is evaluate chanied operations in one step.
- 26. Defender Methods • Before Java 8, Interfaces can contain only abstract methods. • With Java 8, any Interface can contain one or more concrete methods that named default/defender method. • Tip: Default methods do not break nature of F I onctional nterfaces
- 27. Defender Methods • Defender Methods, Default Methods, Virtual extension methods • Makes possible usage of concrete methods. • Makes more elastic of Java Inheritance model.
- 28. Defender Methods • Defender methods can be re-implemented or inherited by other Interfaces.
- 29. ? ?? ??? ???? ????? Q/A ???? ??? ?? ?