Basic Class

class Calculator {
  val brand = "HP"
  def add(m:Integer, n:Integer) = m+n
}

Usage

val cal = new Calculator
println(cal.add(2,3))

Output

5

Constructor

class Calculator(brand:String){
  /**
   * A constructor.
   */
  val color: String = if ("brand" == "TI"){
    "blue"
  } else if ("brand" == "HP") {
    "black"
  } else {
    "white"
  }

  // An instance method
  def add(m:Integer, n:Integer) = m+n
}

Usage

val cal = new Calculator("TI")
println(cal.color)

Output

blue