Scala for android

Do More with Less: Building Android Apps with Scala Tony Hillerson • Tack Mobile AnDevCon III @thillerson @tackmobilePRESENTATION ANDEVCON • MAY 14, 2012

ABOUT METony HillersonSoftware Architect & Partner Mobile design and development company based in Denver, CO.• O’Reilly Screencasts• Computer Nerd @tackmobile• Co-creator of FieldTest tackmobile.com@thillersontony@tackmobile.comPRESENTATION tackmobile.com

Why Would I Consider Scala? • Write less boilerplate code • More powerful features than Java • Move towards Functional paradigmsPRESENTATION tackmobile.com

N.B. I Am Not a Scala Expert • You can probably stump me • This talk is about how you can explore what Scala might do for youPRESENTATION tackmobile.com

My Goals • Introduce you to Scala • Introduce you to Scala with Android • Give you a few good reasons to use Scala • Encourage you to become a PolyglotPRESENTATION tackmobile.com

Be a PolyglotPRESENTATION tackmobile.com

“ Learn one new language per year - The Pragmatic ProgrammersPRESENTATION tackmobile.com

SevenLanguages inSeven Weekshttp://pragprog.com/book/btlang/seven-languages-inseven-weeksPRESENTATION tackmobile.com

What is Scala?PRESENTATION ANDEVCON • MAY 14, 2012

What is Scala? • JVM Language • Take advantage of any Java library • Bridges the divide between OO and Functional spacesPRESENTATION tackmobile.com

scala-lang.orgPRESENTATION tackmobile.com

REPL • Read Execute Print Loop • Command line: scala • Test code quicklyPRESENTATION tackmobile.com

Strongly, Statically Typed • Compile time type checking • Restrictions on how types can be used together • For comparison: • Javascript - Weakly typed, Dynamic • Ruby - Strongly typed, DynamicPRESENTATION tackmobile.com

≠ Boilerplate • Perens are (sometimes) optional • Semicolons are (mostly) optional • Types are inferred, thus: ArrayList<GameTileMotionDescriptor> descriptors = new ArrayList<GameTileMotionDescriptor>(); VS. val descriptors = new ArrayBuffer[GameTileMotionDescriptor]PRESENTATION tackmobile.com

More OO than Java • Everything is an object • Operators are actually methods • For instance, override the “+” methodPRESENTATION tackmobile.com

Functional Language • Functions are first class citizens • High order functions: Functions that operate on functions • Avoids mutable state • Could get pretty academic • Scala bridges the gap between OO and FunctionalPRESENTATION tackmobile.com

A Javascript Functionvar doSomething = function(data) { doSomethingElseWithData(data);}PRESENTATION tackmobile.com

A Scala Functiondef doSomething(data:A):B = { doSomethingElseWithData(data)}PRESENTATION tackmobile.com

Concurrent • Optional immutable state • Actors - Higher concept than Threads/ Thread PoolsPRESENTATION tackmobile.com

Example Conversion ProjectPRESENTATION ANDEVCON • MAY 14, 2012

Slider PuzzlePRESENTATION tackmobile.com

Experiment: Convert from Java to Scala • Android • https://github.com/thillerson/Android-Slider-Puzzle • Scala • https://github.com/thillerson/scala-android-slider-puzzle • Mixed results. • I have a lot to learn about ScalaPRESENTATION tackmobile.com

Mike Burns • Thoughtbot • Android and Scala at Android Open • http://robots.thoughtbot.com/post/ 5836463058/scala-a-better-java-for-android • Ohlaunch - https://github.com/mike-burns/ ohlaunchPRESENTATION tackmobile.com

Scala with AndroidPRESENTATION ANDEVCON • MAY 14, 2012

SBT • Build tool (use for Java too) • https://github.com/harrah/xsbt/wiki/ Getting-Started-WelcomePRESENTATION tackmobile.com

android-plugin • https://github.com/jberkel/android-plugin/ wiki/getting-started • ADB/DDMS Integration • Build and ReleasePRESENTATION tackmobile.com

But I Need My Eclipse! • http://www.assembla.com/wiki/show/scala- ide/Developing_for_AndroidPRESENTATION tackmobile.com

Scala’s Features and IdiomsPRESENTATION ANDEVCON • MAY 14, 2012

vals and vars • var - A variable definition. Required to be initialized when in a function • val - A value definition. Once set, cannot be changed • Basically a “final” • Important consideration for concurrent programmingPRESENTATION tackmobile.com

Methods • Declaration conventions • Suffix notation • Infix notationPRESENTATION tackmobile.com

Looping • for ( item <- items ) • rangesPRESENTATION tackmobile.com

Scala Collections • Scala really shines on collections • A good introduction to functional powerPRESENTATION tackmobile.com

Anonymous Function Syntax • ( args ) => ReturnType • ( x:Int ) => x * xPRESENTATION tackmobile.com

Inheritance in Java • Single Inheritance • Restricting!PRESENTATION tackmobile.com

Inheritance in C++ • Multiple Inheritance • Mind BlownPRESENTATION tackmobile.com

Traits • Mixin pattern • Abstract/Interface + implementationPRESENTATION tackmobile.com

Extending the Language class UnlessClass[T](block: => T) { def unless(b: Boolean): Unit = { if (!b) block } } implicit def toUnlessClass[T](block: => T): UnlessClass[T] = { new UnlessClass[T](block) } ... foo unless flag http://naturalsoftware.blogspot.com/2009/05/ruby-unless-scala.htmlPRESENTATION tackmobile.com

ResourcesPRESENTATION ANDEVCON • MAY 14, 2012

Books on Scala • http://www.scala-lang.org/node/959PRESENTATION tackmobile.com

Positronic • Framework for Android in Scala • Makes use of Actors • http://rst.github.com/tutorial.htmlPRESENTATION tackmobile.com

Assembla • http://www.assembla.com/wiki/show/scala- ide/Developing_for_AndroidPRESENTATION tackmobile.com

SevenLanguages inSeven Weekshttp://pragprog.com/book/btlang/seven-languages-inseven-weeksPRESENTATION tackmobile.com

Recap • Scala is perfect for Android • Consider expanding your mind • Be a PolyglotPRESENTATION tackmobile.com

Thank You @thillerson @tackmobilePRESENTATION ANDEVCON • MAY 14, 2012

Scala for android

by Tack Mobile on May 16, 2012

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