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    How to Install Scala on CentOS 7

    How to Install Scala on CentOS 7

    scala

    Scala is an object-oriented and functional programming language. It a popular language that has been used for developing applications, such as Spark.

    Step 1: Update your system


    [root@monitor ~]# yum update -y

    [root@monitor ~]# reboot

    Step 2: Install OpenJDK


    Scala requires the Java runtime version 1.6 or later.

    [root@monitor ~]# yum install java-1.8.0-openjdk -y

    You can verify your Java installation

    [root@ip-10-0-0-219 ~]# java -version
    openjdk version "1.8.0_242"
    OpenJDK Runtime Environment (build 1.8.0_242-b08)
    OpenJDK 64-Bit Server VM (build 25.242-b08, mixed mode)
    [root@ip-10-0-0-219 ~]#


    Step 3 : You need to set the "JAVA_HOME" and "JRE_HOME" environment variables.


    echo 'export JAVA_HOME=/usr/lib/jvm/jre-1.8.0-openjdk' | sudo tee -a /etc/profile
    echo 'export JRE_HOME=/usr/lib/jvm/jre' | sudo tee -a /etc/profile
    source /etc/profile

    Step 4: Now Verify that your variable are set properly or not:


    [root@monitor home]# echo $JAVA_HOME
    /usr/lib/jvm/jre-1.8.0-openjdk
    [root@monitor home]# echo $JRE_HOME
    /usr/lib/jvm/jre
    [root@monitor home]#


    Step 5: Install Scala


    [root@monitor ~]# wget http://downloads.lightbend.com/scala/2.11.8/scala-2.11.8.rpm
    [root@monitor ~]# yum install scala-2.11.8.rpm
    Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
    Examining scala-2.11.8.rpm: scala-2.11.8-0.noarch
    Marking scala-2.11.8.rpm to be installed
    Resolving Dependencies

    Step 6: Verify your installation:

    [root@monitor ~]# scala -version
    Scala code runner version 2.11.8 -- Copyright 2002-2016, LAMP/EPFL
    [root@monitor ~]#

    How to Use Scala:


    Run the Scala code runner and get into the Scala shell:

    [root@monitor ~]# scala
    Welcome to Scala 2.12.10 (OpenJDK 64-Bit Server VM, Java 1.8.0_242).
    Type in expressions for evaluation. Or try :help.

    scala>

    Example 1: Addition of 2 numbers

    scala> 3+3
    res0: Int = 6

    scala>

    If you want to quit the Scala shell:

    :q

    scala> :q
    [root@monitor ~]#


    Example 2 : Write a code and compile it


    [root@monitor ~]# vi hello.scala
    [root@monitor ~]# cat hello.scala
    object HelloScala {
      def main(args: Array[String]) {
        println("Hello Scala!")
      }
    }
    [root@monitor ~]#

    Compile the source code with scalac:

    scalac hello.scala

    [root@monitor ~]# scalac hello.scala
    [root@monitor ~]#

    The program will generate two compiled files: HelloWorld.class and HelloWorld$.class. You can run the compiled file with scala:

    [root@monitor ~]# ls
    @ hello.scala  HelloScala.class  HelloScala$.class    scala-2.11.8.rpm  scala-2.12.10.rpm
    [root@monitor ~]# scala HelloScala
    Hello Scala!
    [root@monitor ~]#


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