Hanoi jug java 8 stream api

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Java 8: Stream API

Vu Dang Ngoc - eXo

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Introduction to Stream API

1. Stream API at glance

a. Aggregate Operations, Terminal Operations

b. Laziness and performance tuning

2. How Stream API change the way we coding?

3. Advantage and disadvantage

4. Further reading

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Stream example

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Stream API at glance

● Pipeline contain a data source, 1 or many intermediate

operation, 1 terminal operation and linked together by

streams.

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Stream source

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Operations

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Intermediate Operation

● Stream-producing: require a stream and

return another stream

● Always lazy

● Stateless and stateful operations

o Stateless (filter, map …): don’t require information of

other items.

o Stateful (distinct, sorted, limit, peek…): require

information of other items.

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Terminal Operation

● End of pipeline

● Push intermediate operator working

● Short-circuiting: stream don’t have to travel

all data.

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Laziness and performance tuning

● Intermediate operator run only when

Terminate operator asking

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Laziness and performance tuning

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Stream is not loop

continue to next

element

You have no power

here!

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How Stream API change the way we coding?

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● Terminal operator collect provide many way

to transform data

● Collectors class provide built-in collection

feature.

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Parallel stream

● Using Fork-Join Pool

● Side-effect

● Some parallel stream operations like reduce

and collect need additional computations

● All sub-tasks should finish in a reasonable

time

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Parallel stream

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Performance compare

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Parallel stream performance is unstable

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Advantage and Disadvantage

● The Goodo Reduce size of code

o Easy using parallel computing

o Developer can focus how to process data

o Built-in feature of Collectors class

● The Bado No customize operator

o Cannot random access

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Advantage and Disadvantage

● And the Uglyo Stream cannot reuseable

o Parallel stream performance is unstable and

unpredictable

o Stream don’t store data and cannot modify source

collection.

o Can cause infinite stream

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Infinite stream

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Further reading

● Collection Pipes - article of Martin Fowler

about pipe and filter software pattern

● Java Fork-Join Calamity and Java Parallel

Calamity descript flaws of Fork/Join and

parallel stream

● Active vs Passive iterator

● Parallel Streams and Spliterators

http://martinfowler.com/articles/collection-pipeline/

http://www.coopsoft.com/ar/CalamityArticle.html

http://www.coopsoft.com/ar/Calamity2Article.html

http://www.javaworld.com/article/2461744/java-language/java-language-iterating-over-collections-in-java-8.html

http://java.dzone.com/articles/parallel-streams-and

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Referent

● http://www.java2novice.com/java-sorting-

algorithms/quick-sort/

● http://javapapers.com/java/java-stream-api/

● http://winterbe.com/posts/2014/07/31/java8-stream-

tutorial-examples/

● http://www.informit.com/articles/article.aspx?p=2198914

● http://blog.credera.com/technology-insights/java/java-8-

part-1-lamdas-streams-functional-interfaces/

● https://docs.oracle.com/javase/8/docs/api/java/util/strea

m/package-summary.html

● http://java.dzone.com/articles/think-twice-using-java-8

● http://blog.jooq.org/2014/06/13/java-8-friday-10-subtle-

mistakes-when-using-the-streams-api/

http://www.java2novice.com/java-sorting-algorithms/quick-sort/

http://javapapers.com/java/java-stream-api/

http://winterbe.com/posts/2014/07/31/java8-stream-tutorial-examples/

http://www.informit.com/articles/article.aspx?p=2198914

https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html

http://java.dzone.com/articles/think-twice-using-java-8

http://blog.jooq.org/2014/06/13/java-8-friday-10-subtle-mistakes-when-using-the-streams-api/

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Questions & Answers

Hanoi jug java 8 stream api

Software

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