Case class

case class adds a lot of useful features to the normal class. It is handy to build lightweight data structures.

case Person(name: String, age: Int)

val jim = new Person("Jim", 34)

The features are as followed:

1. Class parameters are fields.

   jim.name // It works
   

2. It's sensible to toString.

   println(jim.toString) // output: Person(Jim, 34)
   println(jim) // It's same as the previous line.
   

3. equals is implemented.

   val jim2 = new new Person("Jim", 34)
   println(jim == jim2) // true
   

4. copy is very useful.

   // copy jim and set age to 13
   val jim3 = jim.copy(age = 13)
   

5. Case classes have companion objects

   val mary = Person("Mary", 20)
   

6. Case classes are serializable.

   It's very useful in the framework Akka.

7. Case classes have extractor patterns.

   It means they can be used in pattern matching.

We can also create case object.

case object Cat