mirror of https://github.com/sbt/sbt.git
82 lines
2.5 KiB
Markdown
82 lines
2.5 KiB
Markdown
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# Hello, World
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[[Previous|Getting Started Setup]] _Getting Started Guide page 3 of 14._ [[Next|Getting Started Directories]]
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This page assumes you've [[installed sbt|Getting Started Setup]].
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## Create a project directory with source code
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A valid sbt project can be a directory containing a single source file. Try creating a directory `hello` with a file `hw.scala`, containing the following:
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```scala
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object Hi {
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def main(args: Array[String]) = println("Hi!")
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}
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```
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Now from inside the `hello` directory, start sbt and type `run` at the sbt interactive console. On Linux or OS X the commands might look like this:
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```text
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$ mkdir hello
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$ cd hello
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$ echo 'object Hi { def main(args: Array[String]) = println("Hi!") }' > hw.scala
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$ sbt
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...
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> run
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...
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Hi!
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```
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In this case, sbt works purely by convention. sbt will find the
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following automatically:
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- Sources in the base directory
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- Sources in `src/main/scala` or `src/main/java`
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- Tests in `src/test/scala` or `src/test/java`
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- Data files in `src/main/resources` or `src/test/resources`
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- jars in `lib`
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By default, sbt will build projects with the same version of Scala used to run sbt itself.
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You can run the project with `sbt run` or enter the [Scala REPL](http://www.scala-lang.org/node/2097)
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with `sbt console`. `sbt console` sets up your project's classpath so you can
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try out live Scala examples based on your project's code.
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## Build definition
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Most projects will need some manual setup. Basic build settings go
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in a file called `build.sbt`, located in the project's base directory.
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For example, if your project is in the directory `hello`, in `hello/build.sbt` you might write:
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```scala
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name := "hello"
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version := "1.0"
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scalaVersion := "2.9.1"
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```
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Notice the blank line between every item. This isn't just for show; they're actually required in order to separate each item. In [[.sbt build definition|Getting Started Basic Def]] you'll learn more about how to write a `build.sbt` file.
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If you plan to package your project in a jar, you will want to set at least
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the name and version in a `build.sbt`.
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## Setting the sbt version
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You can force a particular version of sbt by creating a file `hello/project/build.properties`.
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In this file, write:
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```text
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sbt.version=0.12.0
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```
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From 0.10 onwards, sbt is 99% source compatible from release to release. Still,
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setting the sbt version in `project/build.properties` avoids any potential
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confusion.
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# Next
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Learn about the [[file and directory layout|Getting Started Directories]] of an sbt project.
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