{"id":453,"date":"2021-08-12T21:59:19","date_gmt":"2021-08-12T12:59:19","guid":{"rendered":"https:\/\/osmanthus.work\/?p=453"},"modified":"2021-09-02T23:27:16","modified_gmt":"2021-09-02T14:27:16","slug":"hello-world-in-scala","status":"publish","type":"post","link":"https:\/\/osmanthus.work\/?p=453","title":{"rendered":"Various ways to print “Hello world” in Scala"},"content":{"rendered":"\n

1. Introduction<\/h2>\n\n\n\n

I will show the way to build and run program which prints “hello world” without sbt, with sbt, with maven. Here, sbt is “Scala Build Tool”.<\/p>\n\n\n\n

2. Preliminaries<\/h2>\n\n\n\n

Scala Version:2.12<\/p>\n\n\n\n

sbt:1.2.7<\/p>\n\n\n\n

OS:CentOS7<\/p>\n\n\n\n

Java:OpenJDK8<\/p>\n\n\n\n

Maven:3.6.3<\/p>\n\n\n\n

3. Install Scala and Maven<\/h2>\n\n\n\n

Refer to [3]<\/p>\n\n\n\n

4. Hello world without sbt<\/h2>\n\n\n\n

Execute the following procedures[1].<\/p>\n\n\n\n

(1) Create source file.<\/p>\n\n\n\n

vi Hello.scala\n--Hello.scala\nobject Hello {\n    def main(args: Array[String]) = {\n        println(\"Hello, world\")\n    }\n}\n--\n\n<\/code><\/pre>\n\n\n\n
(2) compile<\/p>\n\n\n\n
scalac Hello.scala<\/code><\/pre>\n\n\n\n
(3) run<\/p>\n\n\n\n
scala Hello<\/code><\/pre>\n\n\n\n
5. Hello world with sbt<\/h2>\n\n\n\n
5.1 Install sbt<\/h3>\n\n\n\n
 Execute the following commands[4]. <\/p>\n\n\n\n
curl -L https:\/\/www.scala-sbt.org\/sbt-rpm.repo > sbt-rpm.repo\nsudo mv sbt-rpm.repo \/etc\/yum.repos.d\/\nsudo yum install sbt<\/code><\/pre>\n\n\n\n
5.2 Create project<\/h3>\n\n\n\n
Execute the following command[4]. Let the project name be “hello”.<\/p>\n\n\n\n
sbt new sbt\/scala-seed.g8\ncd hello<\/code><\/pre>\n\n\n\n
5.3 Hello world with sbt shell<\/h3>\n\n\n\n
(1) Compile<\/p>\n\n\n\n
sbt compile<\/code><\/pre>\n\n\n\n
(2) Run<\/p>\n\n\n\n
sbt run<\/code><\/pre>\n\n\n\n
5.4 Hello World with scala<\/h3>\n\n\n\n
pushd .\/target\/scala-2.12\/classes\/\nscala example.Hello\npopd<\/code><\/pre>\n\n\n\n
5.4 Hello world with java<\/h3>\n\n\n\n
(1) Create “plugins.sbt”[7][8].  sbt-assembly is a plugin which create a jar from a project.<\/p>\n\n\n\n
vi .\/project\/plugins.sbt\n--\naddSbtPlugin(\"com.eed3si9n\" % \"sbt-assembly\" % \"0.14.10\")\n--<\/code><\/pre>\n\n\n\n
(2) Compile<\/p>\n\n\n\n
sbt assembly<\/code><\/pre>\n\n\n\n
(3) Run<\/p>\n\n\n\n
java -jar .\/target\/scala-2.12\/hello-assembly-0.1.0-SNAPSHOT.jar<\/code><\/pre>\n\n\n\n
6. Hello world with maven<\/h2>\n\n\n\n
Perform the following steps. For detail, refer to [8].<\/p>\n\n\n\n
(1) Create a maven project.  <\/p>\n\n\n\n
mvn archetype:generate -DarchetypeGroupId=net.alchim31.maven -DarchetypeArtifactId=scala-archetype-simple<\/code><\/pre>\n\n\n\n
(2) Maven ask you some inputs. I put the followings.<\/p>\n\n\n\n
name<\/td>value<\/td><\/tr>
groupid<\/td>group1<\/td><\/tr>
artifactId<\/td>artifact1<\/td><\/tr>
version<\/td>1.0<\/td><\/tr>
package<\/td>package1<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
(3) Add the following  <plugin>…<\/plugin>  part to pom.xml for creating jar file.<\/p>\n\n\n\n
<project ...>\n    <modelVersion>X.X.X<\/modelVersion>\n    ...\n    <licenses>\n        ...\n    <\/licenses>\n\n    <properties>\n        ...\n    <\/properties>\n\n    <dependencies>\n        ...\n    <\/dependencies>\n\n    <build>\n        ...\n        <plugins>\n            ...\n            <plugin>\n                <groupId>org.apache.maven.plugins<\/groupId>\n                <artifactId>maven-assembly-plugin<\/artifactId>\n                <version>2.4<\/version>\n                <configuration>\n                    <descriptorRefs>\n                        <descriptorRef>jar-with-dependencies<\/descriptorRef>\n                    <\/descriptorRefs>\n                    <archive>\n                        <manifest>\n                            <mainClass>com.your-package.MainClass<\/mainClass>\n                        <\/manifest>\n                    <\/archive>\n                <\/configuration>\n                <executions>\n                    <execution>\n                        <phase>package<\/phase>\n                        <goals>\n                            <goal>single<\/goal>\n                        <\/goals>\n                    <\/execution>\n                <\/executions>\n            <\/plugin>\n        <\/plugins>\n    <\/build>\n<\/project><\/code><\/pre>\n\n\n\n
(4) Create jar file.<\/p>\n\n\n\n
mvn package<\/code><\/pre>\n\n\n\n
(5) Execute jar.<\/p>\n\n\n\n
java -jar target\/artifact1-1.0-jar-with-dependencies.jar<\/code><\/pre>\n\n\n\n
7. References<\/h2>\n\n\n\n
[1] SCALA BOOK, HELLO, WORLD<\/p>\n\n\n\n
https:\/\/docs.scala-lang.org\/overviews\/scala-book\/hello-world-1.html<\/a><\/p>\n\n\n\n
[2] Scala Build Tool(sbt)<\/p>\n\n\n\n
https:\/\/docs.scala-lang.org\/overviews\/scala-book\/scala-build-tool-sbt.html<\/a><\/p>\n\n\n\n
[3] Installing Apache Spark from source<\/p>\n\n\n\n
\n
Installing Apache Spark from source<\/a><\/blockquote>