The presumes you have Scala installed on the local system.

This is just the basics on declaring variables in Scala and what data types are available.

Create file src/main/scala/Playground.scala with the following.

object Playground extends App {
  val x: Int = 42
  println(x)
}
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Say we remove the explicit type:

object Playground extends App {
  val x = 42
  println(x)
}
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This still works as the compiler infers the type to be an Int.

Below we will run through a declaration of each type.

object Playground extends App {
  val x: Int = 42
  val y: String = "Hello, Friend!"
  val z: Boolean = true
  val a: Char = 'a' // Note single quotes
  val b: Short = 1234
  val c: Long = 1234123412341234L // Note the L - similar to Java longs
  val d: Float = 2.0f // Note the f - similar to Java
  val e: Double = 2.14 // No marker needed

  /* in order to mutate a variable */
  var f: Int = 1
  f = 2 // this is known as a side effect
}
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Note that the val and var keywords have different meanings. val is a constant and follows functional, immutable conventions while var is mutable and changing a mutable variable is known as a side effect.