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Applying Java 8 Idioms to Existing Code
The document discusses the advantages and features of refactoring code to Java 8, particularly focusing on lambda expressions and the Streams API, showcasing the performance benefits and improvements in code clarity. It highlights the purpose of the QCon conference, which is to foster innovation in software development and to connect influential speakers and topics. The summary emphasizes the need for careful consideration when migrating to Java 8, suggesting that performance should be measured while keeping goals in mind.
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Applying Java 8 Idioms to Existing Code
- 1. Trisha Gee (@trisha_gee) Developer& Technical Advocate, JetBrains Refactoring to Java 8
- 2. InfoQ.com: News &Community Site • 750,000 unique visitors/month • Published in 4 languages (English, Chinese, Japanese and Brazilian Portuguese) • Post content from our QCon conferences • News 15-20 / week • Articles 3-4 / week • Presentations (videos) 12-15 / week • Interviews 2-3 / week • Books 1 / month Watch the video with slide synchronization on InfoQ.com! https://www.infoq.com/presentations/ java8-lambda-streams
- 3. Presented at QConNew York www.qconnewyork.com Purpose of QCon - to empower software development by facilitating the spread of knowledge and innovation Strategy - practitioner-driven conference designed for YOU: influencers of change and innovation in your teams - speakers and topics driving the evolution and innovation - connecting and catalyzing the influencers and innovators Highlights - attended by more than 12,000 delegates since 2007 - held in 9 cities worldwide
- 4.
- 5. It’s Faster •Performance Improvementsin Common Data Structures •Fork/Join Speed Improvements •Changes to Support Concurrency •…and more http://bit.ly/refJ8
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- 7. Fewer Lines ofCode
- 8. New Solutions toProblems
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- 13. Decide on theGoals
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- 22. Automatic Refactoring •For loopto collect •For loop to forEach •…with and without Streams
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- 26. But what aboutperformance?
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- 28. 0 20 40 60 80 100 120 140 160 180Ops/ms Anonymous Inner Classesvs Lambdas Anonymous Inner Class Lambda
- 29. http://www.oracle.com/technetwork/java/jvmls2013kuksen-2014088.pdf 0 2 4 6 8 10 12 14 16 18 20 single thread maxthreads nsec/op Performance of Capture anonymous(static) anonymous(non-static) lambda
- 30. 0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000 500,000 Constant message Variablemessage Ops/ms Logging Performance Direct call Lambda
- 31.
- 32. 0 1 2 3 4 5 6 7 8 9 Ops/ms Iterator vsStream (1000 elements) for loop forEach()
- 33. 0 1000 2000 3000 4000 5000 6000 7000 1 10 1001000 Ops/ms IterHelper original simplified refactored
- 34. 0 1 2 3 4 5 6 7 8 9 1000 10000 100000 Ops/msIterHelper original simplified refactored
- 35. BasicDAO – map& collect
- 36. 0 5000 10000 15000 20000 25000 1 10 1001000 Ops/ms BasicDAO original simplified refactored
- 37. DuplicatedAttributeNames – filter,map & collect
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- 41. DatastoreImpl – filter& forEach
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- 43. MappingValidator – singlestream operation
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- 45. QueryImpl – multipleoperations
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- 51. 0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 Value not nullValue null Ops/ms Compare Constant Field Value with Null Null check Optional
- 52. 0 50,000 100,000 150,000 200,000 250,000 300,000 Value not nullValue null Ops/ms Compare Variable Field Value with Null Null check Optional
- 53.
- 54. Sometimes new idiomsdecrease clutter
- 56. …but sometimes theydon’t
- 58. Sometimes the newfeatures improve performance
- 59. 0 20 40 60 80 100 120 140 160 180Ops/ms Anonymous Inner Classesvs Lambdas Anonymous Inner Class Lambda
- 60. …and sometimes theydon’t
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- 62. Sometimes a newfeature makes life easier
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- 66. Some refactoring cansafely be done automatically
- 68. …often you needa human brain
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- 71. Should you migrateyour code to Java 8?
- 72.
- 73. Always remember whatyour goal is And compare results to it
- 74. Understand what mayimpact performance And if in doubt, measure
- 75. Code may magicallyimprove Or you may expose areas for improvement
- 76. Your tools canhelp you But you need to apply your brain too
- 77.
- 78. Watch the videowith slide synchronization on InfoQ.com! https://www.infoq.com/presentations/java8- lambda-streams