Scala Language Case Classes Case Class Basics
Example
In comparison to regular classes – case classes notation provides several benefits:
-
All constructor arguments are
publicand can be accessed on initialized objects (normally this is not the case, as demonstrated here):case class Dog1(age: Int) val x = Dog1(18) println(x.age) // 18 (success!) class Dog2(age: Int) val x = new Dog2(18) println(x.age) // Error: "value age is not a member of Dog2" -
It provides an implementation for the following methods:
toString,equals,hashCode(based on properties),copy,applyandunapply:case class Dog(age: Int) val d1 = Dog(10) val d2 = d1.copy(age = 15) -
It provides a convenient mechanism for pattern matching:
sealed trait Animal // `sealed` modifier allows inheritance within current build-unit only case class Dog(age: Int) extends Animal case class Cat(owner: String) extends Animal val x: Animal = Dog(18) x match { case Dog(x) => println(s"It's a $x years old dog.") case Cat(x) => println(s"This cat belongs to $x.") }
