Scala Introduction - The Basics

Significant points of Scala

• Developed by Martin Odersky in 2004. 
• Is MultiParadigm - a blend of Functional and Object Oriented Paradigms
• Is statically typed
• Heavily uses Java libraries
• Encourages use of immutable data structures

Basics

• Expressions are computable statements. For example 1+1

• Values are names for results for expressions. Example val x = 1 + 1

  • These are immutable

• Variables are mutable names for expression results. Example var x = 1 + 1

• Blocks are expressions combined together within a {}

  • Result of last expression in block is the result of the block as well.

• Functions are expressions that have params

  • Anonymous functions - (x: Int) => x + 1
  • Named functions - val add1 = (x: Int) = x + 1

• Methods are similar to functions with slight variation in syntax

  • def add1(x: Int): Int = x + 1

• Classes are defined by using class keyword.

  class Abc(name: String) {
        def say(): Unit = println(name)
  }
  val abc = new Abc("Ankush")
  abc.say() // Ankush
  

  • Instances of classes get compared with reference
  • Can inherit only one other class.

• Case Class is special case of class , instances of which are compared with value.

  case class Point(x: Int, y: Int)
  

  • No new is required to instantiate case class.

• Object are single instances of their own defination. For example-

  object ResourceFactory {
      def create() : Int = {
         return 1 // random new resource id
      }
  }
  
  val newResourceId = ResourceFactory.create()
  

• Traits are abstract data types containing fields and methods.

  • Class can extend multiple traits, but only one other class.

• Main method is required by JVM, which acts are entry point of Scala program.

  • Accepts a list of multiple strings.

Source - https://docs.scala-lang.org/tour/basics.html