Scala, Java, Unix, MacOS tutorials (page 155)

Because I think it’s often best to “learn by example,” I’ve become a connoisseur of SBT build.sbt examples, and this build.sbt file from Lihaoyi’s PPrint project demonstrates a lot of SBT variables:

val baseSettings = Seq(
    organization := "com.lihaoyi",
    name := "pprint",
    version := _root_.pprint.Constants.version,
    scalaVersion := "2.11.11",
    testFrameworks := Seq(new TestFramework("utest.runner.Framework")),
    publishTo := Some("releases"  at "https://oss.sonatype.org/service/local/staging/deploy/maven2"),
    crossScalaVersions := Seq("2.10.6", "2.11.11", "2.12.2"),
    scmInfo := Some(ScmInfo(
        browseUrl = url("https://github.com/lihaoyi/PPrint"),
        connection = "scm:git:git@github.com:lihaoyi/PPrint.git"
    )),
    homepage := Some(url("https://github.com/lihaoyi/PPrint")),
    licenses := Seq("MIT" -> url("http://www.opensource.org/licenses/mit-license.html")),
    developers += Developer(
        email = "haoyi.sg@gmail.com",
        id = "lihaoyi",
        name = "Li Haoyi",
        url = url("https://github.com/lihaoyi")
    )
)

baseSettings

lazy val pprint = crossProject.crossType(CrossType.Pure)
  .settings(
    baseSettings,
    scalacOptions ++= Seq(scalaBinaryVersion.value match {
      case x if x.startsWith("2.12") => "-target:jvm-1.8"
      case _ => "-target:jvm-1.7"
    }),
    libraryDependencies ++= Seq(
      "com.lihaoyi" %%% "fansi" % "0.2.4",
      "org.scala-lang" % "scala-reflect" % scalaVersion.value % Provided,
      "org.scala-lang" % "scala-compiler" % scalaVersion.value % Provided,
      "com.lihaoyi" %%% "sourcecode" % "0.1.3",
      "com.lihaoyi" %%% "utest" % "0.4.7" % Test,
      "com.chuusai" %%% "shapeless" % "2.3.2" % Test
    ),

    unmanagedSourceDirectories in Compile ++= {
      if (Set("2.11", "2.12", "2.13.0-M1").contains(scalaBinaryVersion.value))
        Seq(baseDirectory.value / ".." / "src" / "main" / "scala-2.10+")
      else
        Seq()
    } ,
    unmanagedSourceDirectories in Test ++= {
      if (Set("2.11", "2.12", "2.13.0-M1").contains(scalaBinaryVersion.value))
        Seq(baseDirectory.value / ".." / "src" / "test" / "scala-2.10+")
      else
        Seq()
    },
    sourceGenerators in Compile += Def.task {
      val dir = (sourceManaged in Compile).value
      val file = dir/"pprint"/"TPrintGen.scala"

      val typeGen = for(i <- 2 to 22) yield {
        val ts = (1 to i).map("T" + _).mkString(", ")
        val tsBounded = (1 to i).map("T" + _ + ": Type").mkString(", ")
        val tsGet = (1 to i).map("get[T" + _ + "](cfg)").mkString(" + \", \" + ")
        s"""
          implicit def F${i}TPrint[$tsBounded, R: Type] = make[($ts) => R](cfg =>
            "(" + $tsGet + ") => " + get[R](cfg)
          )
          implicit def T${i}TPrint[$tsBounded] = make[($ts)](cfg =>
            "(" + $tsGet + ")"
          )
        """
      }
      val output = s"""
        package pprint
        trait TPrintGen[Type[_], Cfg]{
          def make[T](f: Cfg => String): Type[T]
          def get[T: Type](cfg: Cfg): String
          implicit def F0TPrint[R: Type] = make[() => R](cfg => "() => " + get[R](cfg))
          implicit def F1TPrint[T1: Type, R: Type] = {
            make[T1 => R](cfg => get[T1](cfg) + " => " + get[R](cfg))
          }
          ${typeGen.mkString("\n")}
        }
      """.stripMargin
      IO.write(file, output)
      Seq(file)
    }.taskValue
  )

lazy val pprintJVM = pprint.jvm
lazy val pprintJS = pprint.js

lazy val readme = scalatex.ScalatexReadme(
    projectId = "readme",
    wd = file(""),
    url = "https://github.com/lihaoyi/pprint/tree/master",
    source = "Readme"
).settings(
    scalaVersion := "2.11.8",
    (unmanagedSources in Compile) += baseDirectory.value/".."/"project"/"Constants.scala"
)

Using a sonatype library with SBT

That build.sbt file includes so many variables/settings that I’m not going to try to name them all, but one thing to note is that he publishes his project to sonatype.org. If you want to use PPrint in your own SBT project, that means that you’ll need to include this line in your own build.sbt file:

resolvers += "Sonatype OSS Snapshots" at "https://oss.sonatype.org/content/repositories/snapshots"

That tells SBT to use that URL as another repository it should look in for dependencies you’re trying to include in your project.

As a quick example of how to use a Thread with a basic Handler in an Android application, the following code creates a view where the text in the TextView is updated to show the current date and time when the Button is tapped.

Java source code

First, here’s the Java source code for a file class named ThreadHandlerActivity: