01 Scala Principles 01 Session 01 First Steps

In this exercise you learn to work with a worksheet.

Simply said: a worksheet is an interactive shell. You can enter Scala code in the worksheet and it gets interpreted with immediate results. So let's try it out!

Expressions

Example: Simple expressions like +, *, etc.

  42 / 7                                          //> res6: Int(6) = 6
  40 / 7                                          //> res7: Int(5) = 5
  40d / 7                                         //> res8: Double(5.714285714285714) = 5.714285714285714

'val' and 'var' Variables

Enter the chambers of constant (val) and assignable (var) variables. But remember: "var"s may be nice... but keep in mind: to get a Scala Jedi a best practice is to avoid vars and use only vals as far as possible.

Example: Values - constant variables

  val number1 = 1                                 //> number1  : Int = 1
  val number2: Double = 2                         //> number2  : Double = 2.0
  val number3: BigDecimal = 2                     //> number3  : BigDecimal = 2
  val number4 = number1 + number2 + number3       //> number4  : scala.math.BigDecimal = 5.0

Example: mutable variables

  var i = 0                                       //> i  : Int = 0
  while (i < 2) {
    println(i)
    i += 1
  }                                               //> 0
                                                  //| 1

Classes

Creating your own fun world by defining classes. Use case classes as the sugar in your world!

Example: Class definitions

  class ScalaFun1
  new ScalaFun1                                   //> res0: test.ScalaFun1 = test$$anonfun$main$1$ScalaFun1$1@23964a8d
  class ScalaFun2 {}
  new ScalaFun2                                   //> res1: test.ScalaFun2 = test$$anonfun$main$1$ScalaFun2$1@33ec79b6
  class ScalaFun3 { val message = "Hello, Scala" }
  (new ScalaFun3).message                         //> res2: String = Hello, Scala
  class ScalaFun4 {
    var message = "Hello, Scala"
    def this(anotherMessage: String) {
      this()
      this.message = anotherMessage
    }
  }
  (new ScalaFun4).message                         //> res3: String = Hello, Scala
  (new ScalaFun4("Hello")).message                //> res4: String = Hello