#Usage

Requires sbt and the Android SDK (brew install sbt android-sdk when using homebrew on OSX).

For those who are familiar with the 0.7.x plugin, there is a migration guide for a quick reference. The 0.7.x version is no longer maintained - but it is still available in the 0.7.x branch. Support for the upcoming sbt 0.11 is in the sbt_011 branch.

Using a giter8 template is the easiest way to create a new project that uses the plugin. If you don't have giter8 installed:

$ curl https://raw.github.com/n8han/conscript/master/setup.sh | sh
$ ~/bin/cs n8han/giter8

Now create a new project with one of the Android templates:

$ ~/bin/g8 jberkel/android-app             # sbt 0.10.x
$ ~/bin/g8 jberkel/android-app -b sbt-0_11 # sbt 0.11.x

This will prompt you to customize a few values (press enter to accept defaults), then create the project structure and all needed files plus skeleton tests, specs and activities.

Since this plugin is currently not released you'll have to first build and install it locally by performing the following as described in the "Hacking on the plugin" section.

$ git clone git://github.com/jberkel/android-plugin.git
$ cd android-plugin
$ sbt publish-local

Then, to build the Android package:

$ cd <your app name>
$ export ANDROID_HOME=/path/to/sdk # or ANDROID_SDK_{HOME,ROOT}
$ sbt # enter sbt's interactive mode

> android:package-debug

To install and start the main activity in the Android Emulator (must already be running):

> android:start-emulator

To build a signed package for release into the Marketplace:

> android:prepare-market

##Launching the emulator from sbt

A developer can now fire up the Android Emulator from the sbt terminal (hint: you can get a list of all avds with tab completion)

> android:emulator-start <my_avd>

To list all devices or emulators

> android:list-devices

To stop the emulator:

> android:emulator-stop

##Scala Versions

The version of Scala that sbt compiles your project against is configured in the scalaVersion property in the project/build.scala file. You can set this to any Scala version.

Whenever you change build versions, you'll need to run update again to fetch dependencies. For more information, see the sbt documentation on cross-building.

##Android manifest files

If you would like your AndroidManifest.xml file to automatically inherit versionName and versionCode from your SBT project, add the AndroidManifestGenerator.settings build settings to your project. It will look for an AndroidManifest.xml file, and add versionName and versionCode to that template.

##Typed resources references

As an enhancement to the Android build process, this plugin can generate typed references to application layout elements. To enable, add the TypedResources.settings build settings into your sbt project definition. During compilation a file TR.scala will be generated under src_managed/main/scala.

Typed resource references are created in an object TR (similar to Android's standard R). These are handled by the method findView defined in the traits TypedView and TypedActivity. There are also implicit conversions defined in the object TypedResource; import these to add the method on demand to any views and activities in scope. The findView method casts the view to the known resource type before returning it, so that application code can avoid the redundancy of casting a resource to a type it has declared in the resource definition.

Since Android's resource IDs are scoped to the application, a warning is issued by the plugin when the same ID is used for different types of a resources; the type of resources retrieved by that ID will be unpredictable.

ProGuard optimizations

The plugin allows to run ProGuard optimizations on your classes. This might improve the performance of your application dramatically, but also break it easily. By default, the application is only shrinked by ProGuard, but not optimized.

If you want to apply optimizations, you specify ProGuard optimization options in your project like this:

  lazy val someOptimizedProject = Project(
    id = ...,
    ...
    settings = ... ++ inConfig(Android)(
        proguardOptimizations := Seq(
          "-optimizationpasses 8",
          "-dontpreverify",
          "-allowaccessmodification",
          "-optimizations !code/simplification/arithmetic"
        )
    )
  )

Please note that you will receive even more warnings from ProGuard and dex when you apply optimizations.

Getting screenshots

In the sbt console run:

> android:screenshot-emulator

or

> android:screenshot-device

The screenshots will be written to emulator.png / device.png in the project root directory.

Fetch hprof memory dumps

> android:hprof-emulator
> android:hprof-device

##Building Java Android projects with sbt

If you don't use Scala yet and want to use the plugin to build your existing Java app you can do by adding the PlainJavaProject.settings to your settings:

object AndroidBuild extends Build {
  lazy val main = Project (
    "My Project",
    file("."),
    settings = General.fullAndroidSettings ++ PlainJavaProject.settings
  )
}

This will change the defaults to the directory structure expected by Android's build.xml file and skip the Proguard optimisation step.

##Building Android NDK projects

There is some basic NDK support in the android-plugin. For now, it doesn't do anything else than call ndk-build during compilation and clean up the obj and libs directories during cleanup. This depends on an environment variable being set up: either ANDROID_NDK_HOME or ANDROID_NDK_ROOT.

Place your Android NDK sources in src\main\jni. Add the AndroidNdk.settings to your project:

  lazy val someProjectUsingNDK = Project(
    id = ...,
    ...
    settings = ... ++ AndroidBase.settings ++ AndroidNdk.settings
  )

Hacking on the plugin

If you need make modifications to the plugin itself, you can compile and install it locally (you need at least sbt 0.10.x to build it):

$ git clone git://github.com/jberkel/android-plugin.git
$ cd android-plugin
$ sbt publish-local

##Mailing list

There's no official mailing list for the project but most contributors hang out in scala-on-android or simple-build-tool.

##Credits

This code is based on work by Walter Chang (saisiyat), turned into a plugin by Mark Harrah, and maintained by Jan Berkel.

A lot of people have contributed to the plugin; see contributors for a full list.