Scala on Android - The current state of affairs

An overview of the current state of affairs when developing Android apps with Scala, and examine why contrary to popular belief it is ready for prime time. We will discover some of the tools and more useful libraries, and explore how Scala on Android helps circumvent most of the limitations of Java and the Android SDK

Transcript

1. (Scala on Android) 㱺 The current state of affairs 1
   

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2. whoami
   㱺 CTO & Co-Founder at 47 Degrees, a global
   consulting agency & Typesafe Consulting Partner.
   @raulraja
   @47deg
   http://47deg.com/blog
   (Scala on Android) 㱺 The current state of affairs 2
   

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3. Build Tools
   (Scala on Android) 㱺 The current state of affairs 3
   

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4. SBT 㱺 Android SDK Plugin
   https://github.com/pfn/android-sdk-plugin
   (Scala on Android) 㱺 The current state of affairs 4
   

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5. SBT 㱺 Android SDK Plugin
   — Supports all Android SDK tasks
   — dex
   — typedResourcesGenerator
   — proguard
   — buildConfigGenerator
   — (+ 20... more)
   (Scala on Android) 㱺 The current state of affairs 5
   

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6. SBT 㱺 Android SDK Plugin 㱺 typedResourcesGenerator
   object TR {
   val title = TypedResource[TextView](R.id.title)
   object layout {
   val abc_screen_toolbar = TypedLayout[ActionBarOverlayLayout](R.layout.abc_screen_toolbar)
   }
   }
   class MyActivity extends TypedActivity {
   val titleTextView = findView(title) //titleTextView inferred as TextView, no casting needed
   }
   (Scala on Android) 㱺 The current state of affairs 6
   

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7. SBT 㱺 Android SDK Plugin 㱺 proguard
   Size Matters
   Scala byte code size reduced ~ (2.8M)
   (Scala on Android) 㱺 The current state of affairs 7
   

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8. SBT 㱺 Android SDK Plugin
   — https://github.com/pfn/android-sdk-plugin
   — Active
   — Fast (incremental compilation and proguard
   caching)
   — Proguard + MultiDexApplication integration
   (Circumvents 65K method limit)
   — Supports AAR, JAR and APK artifact types
   (Scala on Android) 㱺 The current state of affairs 8
   

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9. IDE Support
   (Scala on Android) 㱺 The current state of affairs 9
   

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10. IntelliJ IDEA 㱺 Syntax Highlighting
    (Scala on Android) 㱺 The current state of affairs 10
    

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11. IntelliJ IDEA 㱺 Android + Scala + SBT
    (Scala on Android) 㱺 The current state of affairs 11
    

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12. IntelliJ IDEA
    — Active
    — Syntax Highlighting
    — Code assistance
    — Android Studio : Based on IntelliJ
    > Google says: If you have been using Eclipse
    with ADT, be aware that Android Studio is now the
    official IDE for Android
    (Scala on Android) 㱺 The current state of affairs 12
    

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13. Libraries
    (Scala on Android) 㱺 The current state of affairs 13
    

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14. Libraries 㱺 Scaloid 㱺 Simplifying the Android SDK
    //plain vanilla scala
    val button = new Button(context)
    button.setText("Greet")
    button.setOnClickListener(new OnClickListener() {
    def onClick(v: View) {
    Toast.makeText(context, "Hello!", Toast.LENGTH_SHORT).show()
    }
    })
    layout.addView(button)
    (Scala on Android) 㱺 The current state of affairs 14
    

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15. Libraries 㱺 Scaloid 㱺 Simplifying the Android SDK
    //with Scaloid
    SButton("Greet", toast("Hello!"))
    (Scala on Android) 㱺 The current state of affairs 15
    

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16. Libraries 㱺 Scaloid 㱺 XML-less layouts
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="wrap_content" android:padding="20dip">
    android:layout_height="wrap_content" android:text="Sign in"
    android:layout_marginBottom="25dip" android:textSize="24.5sp"/>
    android:layout_height="wrap_content" android:text="ID"/>
    android:layout_height="wrap_content" android:id="@+id/userId"/>
    android:layout_height="wrap_content" android:text="Password"/>
    android:layout_height="wrap_content" android:id="@+id/password"
    android:inputType="textPassword"/>
    android:layout_height="wrap_content" android:id="@+id/signin"
    android:text="Sign in"/>
    
    (Scala on Android) 㱺 The current state of affairs 16
    

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17. Libraries 㱺 Scaloid 㱺 XML-less layouts
    //with scaloid
    new SVerticalLayout {
    STextView("Sign in").textSize(24.5 sp).<>
    STextView("ID")
    SEditText()
    STextView("Password")
    SEditText() inputType TEXT_PASSWORD
    SButton("Sign in")
    }.padding(20 dip)
    (Scala on Android) 㱺 The current state of affairs 17
    

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18. Libraries 㱺 Scaloid 㱺 Futures & Async
    //plain scala
    new AsyncTask[String, Void, String] {
    def doInBackground(params: Array[String]) = {
    doAJobTakeSomeTime(params)
    }
    override def onPostExecute(result: String) {
    alert("Done!", result)
    }
    }.execute("param")
    (Scala on Android) 㱺 The current state of affairs 18
    

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19. Libraries 㱺 Scaloid 㱺 Futures & Async
    //scaloid
    Future {
    val result = doAJobTakeSomeTime(params)
    runOnUiThread(alert("Done!", result))
    }
    (Scala on Android) 㱺 The current state of affairs 19
    

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20. Libraries 㱺 Macroid 㱺 Functional UI with Macros
    import macroid._
    import macroid.FullDsl._
    class GreetingActivity extends Activity with Contexts[Activity] {
    override def onCreate(savedInstanceState: Bundle) = {
    super.onCreate(savedInstanceState)
    // the layout goes here
    setContentView {
    getUi {
    l[LinearLayout](
    w[Button],
    w[TextView]
    )
    }
    }
    }
    }
    (Scala on Android) 㱺 The current state of affairs 20
    

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21. Libraries 㱺 Macroid 㱺 UI composition
    // ActivityContext is an Android Context obtained from an Activity
    import macroid.ActivityContext
    ...
    def layout1(implicit ctx: ActivityContext) =
    l[LinearLayout](
    w[TextView]
    )
    def layout2(implicit ctx: ActivityContext) =
    l[FrameLayout](
    w[ProgressBar]
    )
    def layout3(implicit ctx: ActivityContext) =
    l[FrameLayout](
    layout1,
    layout2
    )
    ...
    (Scala on Android) 㱺 The current state of affairs 21
    

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22. Libraries 㱺 Macroid 㱺 Tweaks
    l[LinearLayout](
    // set button caption
    w[Button] // set text and hide for the time being
    w[TextView] // set layout orientation
    ) (Scala on Android) 㱺 The current state of affairs 22
    

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23. Libraries 㱺 Macroid 㱺 Tweaks Composition
    // AppContext is an Android Context obtained from getApplicationContext
    import macroid.AppContext
    // More tweaks
    import macroid.contrib.TextTweaks
    def greeting(greeting: String)(implicit appCtx: AppContext) =
    TextTweaks.large +
    text(greeting) +
    hide
    (Scala on Android) 㱺 The current state of affairs 23
    

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24. Libraries 㱺 Macroid 㱺 Events
    button ...
    }
    (Scala on Android) 㱺 The current state of affairs 24
    

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25. Libraries 㱺 Macroid 㱺 Slots
    // create a slot
    var greeting = slot[TextView]
    l[LinearLayout](
    w[TextView] // wire the view to the slot
    wire(greeting) OurTweaks.greeting("Hello!"),
    w[Button] text("Click me") On.click {
    // use the slot elsewhere
    greeting }
    ) (Scala on Android) 㱺 The current state of affairs 25
    

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26. Libraries 㱺 Macroid 㱺 Contexts
    class MyActivity extends Activity with Contexts[Activity] {
    // implicit access to AppContext & ActivityContext stored as a weak reference
    }
    class MyFragment extends Fragment with Contexts[Fragment] {
    // implicit access to AppContext & ActivityContext stored as a weak reference
    }
    (Scala on Android) 㱺 The current state of affairs 26
    

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27. Libraries 㱺 Macroid 㱺 Contexts
    class MyActivity extends Activity with Contexts[Activity] {
    // implicit access to AppContext & ActivityContext stored as a weak reference
    }
    class MyFragment extends Fragment with Contexts[Fragment] {
    // implicit access to AppContext & ActivityContext stored as a weak reference
    }
    No need to explicitly pass the context around!
    (Scala on Android) 㱺 The current state of affairs 27
    

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28. Libraries 㱺 Macroid 㱺 Snails
    val focusLoudly = Snail[View] { view 㱺
    view.setFocus()
    playSound
    }
    (Scala on Android) 㱺 The current state of affairs 28
    

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29. Libraries 㱺 Macroid 㱺 Snails composition
    val wink = fadeIn ++ fadeOut
    (Scala on Android) 㱺 The current state of affairs 29
    

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30. Libraries 㱺 Macroid 㱺 Snails & Tweaks combined
    editText (Scala on Android) 㱺 The current state of affairs 30
    

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31. Libraries 㱺 Macroid 㱺 Easy workflows
    (myProgressBar (myTextView (myOtherTextView (Scala on Android) 㱺 The current state of affairs 31
    

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32. Libraries 㱺 Macroid 㱺 Transformers
    linearLayout case t: TextView 㱺 t case i: ImageView 㱺 i }
    (Scala on Android) 㱺 The current state of affairs 32
    

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33. Libraries 㱺 Macroid 㱺 Adaptive (Media queries)
    object OurTweaks {
    def orient(implicit appCtx: AppContext) =
    landscape ? horizontal | vertical
    }
    ...
    // in layout
    l[LinearLayout](
    ...
    ) (Scala on Android) 㱺 The current state of affairs 33
    

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34. Libraries 㱺 Macroid 㱺 Viewable
    Brings the power of Typeclasses to UI composition.
    How to display A using W.
    libraryDependencies += aar("org.macroid" %% "macroid-viewable" % "2.0.0-M3")
    trait Viewable[A, +W (Scala on Android) 㱺 The current state of affairs 34
    

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35. Libraries 㱺 Macroid 㱺 Viewable
    import macroid.viewable.Viewable
    case class User(name: String)
    def userViewable(
    implicit ctx: ActivityContext,
    appCtx: AppContext): Viewable[User, TextView] =
    Viewable[User] { user 㱺
    w[TextView] }
    (Scala on Android) 㱺 The current state of affairs 35
    

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36. Libraries 㱺 Macroid 㱺 Akka Fragments
    Handling Fragment events & messaging with Actors.
    class MyActor extends FragmentActor[MyFragment] {
    def receive = receiveUi andThen {
    case MyMessage(x) 㱺 ...
    case MyOtherMessage 㱺 withUi(fragment 㱺 Ui {
    // do some cool ui stuff here
    })
    case FragmentActor.AttachUi(_) 㱺 ...
    case FragmentActor.DetachUi(_) 㱺 ...
    }
    }
    (Scala on Android) 㱺 The current state of affairs 36
    

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37. OS Apps 㱺 Translate Bubble
    https://play.google.com/store/apps/details?id=com.fortysevendeg.translatebubble
    https://github.com/47deg/translate-bubble-android
    (Scala on Android) 㱺 The current state of affairs 37
    

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38. OS Apps 㱺 Scala Days Official App
    https://play.google.com/store/apps/details?id=com.fortysevendeg.android.scaladays
    https://github.com/47deg/scala-days-android
    (source code available on March 15th)
    (Scala on Android) 㱺 The current state of affairs 38
    

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39. OS Apps 㱺 Scala API Demos
    https://play.google.com/store/apps/details?id=com.fortysevendeg.scala.android
    https://github.com/47deg/scala-android
    (Scala on Android) 㱺 The current state of affairs 39
    

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40. Thank you
    @raulraja
    @47deg
    raul at 47deg.com
    http://47deg.com/blog
    https://speakerdeck.com/raulraja/scala-on-android-the-current-state-of-
    affairs
    https://github.com/47deg/scala-on-android-deck
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