Stream vs. LINQ = jLinqer

"jLinqer" is a Java implementation of LINQ.
https://github.com/k--kato/jLinqer

Transcript

1. Stream vs. LINQ Keisuke KATO @k_kato
2. async function aboutMe() { let profile = { name: “Keisuke Kato” , twitter: “@k_kato” }; return await followTwitterAsync(profile); }
3. Stream vs. LINQ ‡Wikipedia, “Language Integrated Query”, https://en.wikipedia.org/wiki/Language_Integrated_Query ‡Wikipedia, “Anders Hejlsberg”, https://en.wikipedia.org/wiki/Anders_Hejlsberg ‡O'reilly, ”C#: Yesterday, Today, and Tomorrow: An Interview with Anders Hejlsberg, Part 1”, http://archive.oreilly.com/pub/a/dotnet/2005/10/17/interview-with-anders-hejlsberg.html Stream LINQ Language Java C#, F#, VB, Delphi Since 2014 2007 Developer Oracle Microsoft Influenced by ? SQL, Haskell
4. Stream? LINQ?
5. All you need is metaphors ‡Wikipedia, George Lakoff and Mark Johnson, “Conceptual metaphor”, https://en.wikipedia.org/wiki/Conceptual_metaphor
6. Software Metaphors ‡Steve McConnell, “Code Complete, Second Edition”, https://www.safaribooksonline.com/library/view/code-complete-second/0735619670/ch02s03.html David Gries science 1981 Donald Knuth art 1998 Watts Humphrey process 1989 P. J. Plauger and Kent Beck driving a car 1993, 2000 Alistair Cockburn game 2002 Eric Raymond bazaar 2000 Andy Hunt and Dave Thomas gardening 1999 Paul Heckel filming Snow White and the Seven Dwarfs 1994 Fred Brooks farming, hunting werewolves, or drowning with dinosaurs in a tar pit 1995
7. Stream by Google
8. Stream ‡Google, “stream”, https://www.google.co.jp/search?q=stream&source=lnms&tbm=isch
9. Eh... As a river's running
10. LINQ by Google
11. LINQ ‡Google, “linq”, https://www.google.co.jp/search?q=linq&source=lnms&tbm=isch
12. Love in Qushu
13. ‡Shueisha Bunko, “Kawano ngare no yoni”, http://bunko.shueisha.co.jp/yomi/0105_4.html ‡LinQ, http://loveinq.com/ VS.
14. LINQ = Idols
15. Members
16. filter vs. Where
17. filter vs. Where Java C# @Test public void filter() throws Exception { // arrange List<Integer> list = Arrays.asList(1, 2, 3); // act Stream<Integer> stream = list.stream().filter(x -> x == 1 || x == 3); List<Integer> actual = stream.collect(Collectors.toList()); // assert assertEquals(true, actual.contains(1)); assertEquals(false, actual.contains(2)); assertEquals(true, actual.contains(3)); } [TestMethod] public void Where() { // arrange List<int> list = new List<int>() { 1, 2, 3 }; // act IEnumerable<int> enumerable = list.Where(x => x == 1 || x == 3); List<int> actual = enumerable.ToList(); // assert Assert.AreEqual(true, actual.Contains(1)); Assert.AreEqual(false, actual.Contains(2)); Assert.AreEqual(true, actual.Contains(3)); }
18. sort vs. OrderBy
19. sort vs. OrderBy Java C# @Test public void orderBy() { // arrange java.util.List<String> list = Arrays.asList("b", "c", "a"); // act Stream<String> stream = list.stream().sorted(); List<String> actual = stream.collect(Collectors.toList()); // assert assertEquals("a", actual.get(0)); assertEquals("b", actual.get(1)); assertEquals("c", actual.get(2)); } [TestMethod] public void Where() { // arrange List<string> list = new List<string>() { “b”, “c”, “a” }; // act IEnumerable<string> enumerable = list.OrderBy(x => x); List<string> actual = enumerable.ToList(); // assert Assert.AreEqual(“a”, actual[0]); Assert.AreEqual(“b”, actual[1]); Assert.AreEqual(“c”, actual[2]); }
20. so? whatever?
21. ‡Shueisha Bunko, “Kawano ngare no yoni”, http://bunko.shueisha.co.jp/yomi/0105_4.html ‡LinQ, http://loveinq.com/
22. Stream + LINQ = jLinqer ‡Qiita, “Java に C# の LINQ を移植してみた – jLinqer”, http://qiita.com/k--kato/items/ec7ab8b392fa8bb0a732
23. Stream + LINQ = jLinqer ‡GutHub, “jLinqer”, https://github.com/k--kato/jLinqer LINQ(C#) jLinqer(Java) Stream(Java) ThenBy thenBy n/a ThenByDescending thenByDescending n/a SkipWhile skipWhile n/a TakeWhile takeWhile n/a Intersect intersect n/a Union union n/a Except except n/a Reverse reverse n/a SequenceEqual sequenceEqual n/a OfType ofType n/a ElementAt elementAt n/a
24. jLinqer @ Maven Central ‡Maven Central, “jLinqer”, https://oss.sonatype.org/content/groups/public/com/github/jlinqer/jlinqer/0.1.0/ ‡Sonatype. “Community Support - Open Source Project Repository HostingOSSRH-16339”, https://issues.sonatype.org/browse/OSSRH-16339 <dependency> <groupId>com.github.jlinqer</groupId> <artifactId>jlinqer</artifactId> <version>0.1.0</version> </dependency>
25. Type-Erasure Problem ‡stackoverflow, “Generic method to perform a map-reduce operation. (Java-8)”, http://stackoverflow.com/questions/30826674/generic-method-to-perform-a-map-reduce-operation-java-8
26. Demo
27. Thanks! Questions?