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Scala 2.10 : Install2019/12/13

 
Install Scala 2.10.
[1] Make sure the current enabled version of Scala and Install it.
[root@dlp ~]#
dnf module list scala

CentOS-8 - AppStream
Name  Stream   Profiles  Summary
scala 2.10 [d] common [d A hybrid functional/object-oriented language for the JV
               ]         M
Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled

# install Scala 2.10

[root@dlp ~]#
dnf module -y install scala:2.10
[root@dlp ~]#
scala -version

Scala code runner version 2.10.6 -- Copyright 2002-2013, LAMP/EPFL
[2] Run Scala REPL (Read Eval Print Loop) which is the interactive shell to Test Scala.
[root@dlp ~]#
scala

Welcome to Scala version 2.10.6 (OpenJDK 64-Bit Server VM, Java 1.8.0_232).
Type in expressions to have them evaluated.
Type :help for more information.

# print words
scala> println("Hello Scala World")
Hello Scala World

# set constants
scala> val msg:String = "Hello Scala World"
msg: String = Hello Scala World

scala> println(msg)
Hello Scala World

# exit
scala> sys.exit
[3] Create a sample program to Test Scala.
[root@dlp ~]#
vi readfile.scala
import java.io.File
import java.io.FileReader
import java.io.BufferedReader

object readfile {
  def main(args: Array[String]) {
    val reader = new BufferedReader(new FileReader(new File("/etc/passwd")))
    try {
      var line : String = null
        while ({ line = reader.readLine; line != null }) {
          println(line)
        }
    } finally {
      reader.close
    }
  }
}

# run as a script

[root@dlp ~]#
scala readfile.scala

root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
.....
.....

# compile and run

[root@dlp ~]#
scalac readfile.scala

[root@dlp ~]#
total 16
-rw-------. 1 root root 1534 Oct 12 22:40  anaconda-ks.cfg
-rw-r--r--. 1 root root 1104 Dec 13 19:10 'readfile$.class'
-rw-r--r--. 1 root root  574 Dec 13 19:10  readfile.class
-rw-r--r--. 1 root root  387 Dec 13 19:10  readfile.scala

[root@dlp ~]#
scala readfile

root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
.....
.....
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