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Enhancements in Java 9 Streams
This document summarizes new enhancements to the Java Streams API in Java 9, including the addition of takeWhile, dropWhile, ofNullable methods as well as performance improvements to the iterate method. It provides examples of how each new method works and why they are useful, such as takeWhile and dropWhile being potentially more efficient than filter in some cases. It also shows performance test results indicating that streams in Java 9 are faster than in Java 8. In addition, background information is given on streams, monads, and existing stream methods from Java 8 like filter, map, and collect.
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Enhancements in Java 9 Streams
- 1. Java Streams API Enhancementsto Java 9 Corneil du Plessis
- 2. About Me • Workingas Programmer since 1985 • Smallest to very large systems. • Cobol, Fortran, Pascal, Algol, C/C++, Java, JavaScript, Groovy, Python, Scala, Kotlin and more. • Scientific instrumentation, Sports event management, Mining, Banking, Treasury and Insurance. • Software Architect (with a preference for coding)
- 3. Quote Divide each difficultyinto as many parts as is feasible and necessary to resolve it. René Descartes Thank you to Venkat Subramaniam
- 4. Streams – APrimer • Streams are Monads • In functional programming, a monad is a structure that represents computations defined as sequences of steps. A type with a monad structure defines what it means to chain operations, or nest functions of that type together. • Simplistic: Pipeline of Iterators where you apply functions to create new Collections
- 5. Introduction • What areJava Streams? • Aren’t Streams slow? • Enhancements in Java 9
- 6. Streams – Java8 Name Description Result filter Returns a stream with elements matching predicate Stream<T> map Returns a stream Of type and values return by mapper Stream<R> limit Truncate the stream Stream<T> skip Returns a stream after first N elements Stream<T> distinct Returns a stream with only unique elements using equals Stream<T> sorted Returns a stream with elements sorted using natural order or comparator Stream<T> collect Use collector to create new object like List C reduce Applies reduction function like concatenation or summation R forEach Applies function to elements void iterate Produces stream using seed and function Stream<T>
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- 9. Streams – PerformanceComparison Method Throughput Error m1 (Imperative) 1653681.197 ops/s 24178.799 ops/s m2 (Streams) Java 8 1705339.328 ops/s 22440.688 ops/s m2 (Streams) Java 9 1858807,026 ops/s 10793,995 ops/s
- 10. Streams – Java9 enhancements • New • takeWhile • dropWhile • ofNullable • Enhanced • iterate
- 11. Streams – Java9 - takeWhile
- 12. Streams – Java9 - dropWhile
- 13. Streams – Java9 – dropWhile / takeWhile • Not useful for unordered collections. • Can be cheaper than filter
- 14. Streams – Java9 - ofNullable
- 15. Streams – Java9 - ofNullable • Improves handling of null. • Removes boilerplate
- 16. Streams – Java9 - iterate
- 17. Finally • Slides -https://www.slideshare.net/CorneilduPlessis/enhancements- in-java-9-streams • Source Code - https://github.com/corneil/streams-samples • Resources • http://www.oracle.com/technetwork/articles/java/ma14-java-se-8-streams- 2177646.html • http://www.baeldung.com/java-9-stream-api Questions?