Programming Android Application in Scala.

Programming Android Application in Scala BrianHsu / OSDC.2010

關於我

墳墓 (BrianHsu)

表面上軟體工程師

實際上萌系阿宅

入用侵萌藍化星的是手也機

僕我了最　寫！喜　 Android 歡女　　　全我都要是讓是萌女手僕上燃程！機的式

用 Java 寫程式卻燃不起來

高手大師兄

聽說高手都要精通 Multiple Language……

ASE+Ruby/Python/Perl

寫作 Dynamic Scripting Language

唸作快、狠、準

等等

還要先裝 Runtime 啊？

等等

動態型別？

def boom puts "Hello World" end puts " 一個小小的 typo" booom 執行期爆炸

結論

我是懦夫不敢用 ASE

What is Scala?

樓梯

A Postfunctional Programming Language on Java Virtual Machine

Compile to JVM .class Byte Code

理論上 Full Java Interoperability

可以直接拿來寫 Android Application

What is Scala?

A Scalable Language

會隨 User 變形的程式語言

A Scalable Language

Why Scala?

三個願望一次滿足

REPL Scripting Compiling

Scripting

Compiling

Procedure Object Oriented Functional

Procedure Programming

Object Oriented Programming

Functional Programming

Concise Static Typing Duck Typing

Concise (Ruby)

Concise (Scala)

Static Typing (Ruby)

Static Typing (Scala)

真、 Duck Typing (Ruby)

偽‧ Duck Typing (Scala)

結論

有 Scala 、無懦夫

僕我　用了最　 Scala ！喜歡女　　　寫全我都要是萌是讓女手燃程僕上！機的式

Scala vs Java

Scala compared to Java Scala adds Scala removes + a pure object system - static members + operator overloading - primitive types + closures - break, continue + mixin composition with traits - special treatment of interfaces + existential types - wildcards + abstract types - raw types + pattern matching - enums Modeled in libraries: assert, enums, properties, events, actors, using, queries, …

Scala cheat sheet (1): Definitions Scala method definitions: Java method definition: def fun(x: Int): Int = { int fun(int x) { result return result } } def fun = result (no parameterless methods) Scala variable definitions: Java variable definitions: var x: Int = expression int x = expression val x: String = expression final String x = expression

Scala cheat sheet (2): Expressions Scala method calls: Java method call: obj.meth(arg) obj.meth(arg) obj meth arg (no operator overloading) Scala choice expressions: Java choice expressions, stmts: if (cond) expr1 else expr2 cond ? expr1 : expr2 if (cond) return expr1; else return expr2; expr match { case pat1 => expr1 switch (expr) { .... case pat1 : return expr1; case patn => exprn ... } case patn : return exprn ; } // statement only

Scala cheat sheet (3): Objects and Classes Scala Class and Object Java Class with statics class Sample { class Sample(x: Int, val p: Int) { private final int x; def instMeth(y: Int) = x + y public final int p; } Sample(int x, int p) { this.x = x; object Sample { this.p = p; def staticMeth(x: Int, y: Int) = } x*y int instMeth(int y) { } return x + y; } static int staticMeth(int x, int y) { return x * y; } }

Scala cheat sheet (4): Traits Java Interface Scala Trait trait T { interface T { int abstractMth(String x) def abstractMth(x: String): Int } def concreteMth(x: String) = x + field (no concrete methods) var field = “!” (no fields) } Java extension + implementation: Scala mixin composition: class C extends Super implements T class C extends Super with T

當機器人爬上樓梯

Android Application 開發流程

Java / ANT

$ android create project -p … $ vim ..... $ ant install

http://asantoso.wordpress.com/2009/09/15/how-to-build-android-application-package- apk-from-the-command-line-using-the-sdk-tools-continuously-integrated-using- cruisecontrol/

XML 地獄 ANT

Perfect SBT

Simple Build Tool

以 Scala 為 Host Language

Rake=>Ruby SBT =>Scala

不用任何設定支援連續編譯

Android-Plugin

android-plugin http://github.com/jberkel/android-plugin project/build/MyProject.scala

android-plugin

我不會用功能完整

阿宅的通病自己寫一個

sbt-android project/build/MyProject.scala

sbt-android project/plugins/Plugins.scala

Live Demo

Install SBT/SBT-Android ● Install SBT ● http://code.google.com/p/simple-build-tool/ ● Download SBT-Android ● $ git clone http://github.com/brianhsu/sbt-android.git ● Install SBT-Android ● $ cd sbt-android ● $ sbt publish-local

Create Android/Scala Project ● Create SBT project ● $ mkdir AndroidTest ● $ cd AndroidTest ● $ sbt ● Edit project/build/MyProject.scala ● Edit project/plugins/Plugins.scala ● $ sbt update

Android/Scala Project Struture

Build Scala/Android Project ● $ sbt action ● $ sbt install ● $ sbt android-compile ● $ sbt proguard ● $ sbt zipalign ● $ ...

Scala in Android

Trait 是好幫手

SQL 再見！ Collection 最高！

善用偽 Duck Typing

結論可以把 Java 丟了……應該唄？

等等，這是孔明的陷阱！

Scala 的限制與臭蟲 ● 限制 ● Cannot acess static protected Java field. – 對不起， Google Maps API 用到了。 ● 臭蟲 ● Static Java Inner class 造成 classfile borken / Missing dependency missing dependcy – Google Maps API 踩到地雷了 ● Cyclic dependcy – Google Data API 中計了 – 以於 Scala 2.8 main trunk 中修正 ● 解決方式 ● 用 Java 寫個 Wrapper 唄

Thanks!

http://jimmynote.blogspot.com	121
http://blog.lifetaiwan.net	121
http://bone.twbbs.org.tw	118
http://www.slideshare.net	70
http://endroid.blogspot.com	46
http://www.jingege.me	35
http://jimmynote.blogspot.tw	20
http://paper.li	3
http://jimmynote.blogspot.hk	3
http://webcache.googleusercontent.com	3
http://twitter.com	2
http://bone.forestlife.info	2
http://static.slidesharecdn.com	1
http://coderwall.com	1
http://reader.youdao.com	1

Programming Android Application in Scala.

by Brian Hsu

Accessibility

Categories

Upload Details

Usage Rights

15 Embeds 547

Statistics