Case class

In Scala, we define most data structures using case classes. case class has one to many immutable attributes and provides several built-in functions compared to a standard class.

Type the following into the worksheet:

case class Person(name: String, age: Int)
val mikaelNew = new Person("Mikael", 41)
// 'new' is optional
val mikael = Person("Mikael", 41)
// == compares values, not references
mikael == mikaelNew
// == is exactly the same as .equals
mikael.equals(mikaelNew)
 
val name = mikael.name
 
// a case class is immutable. The line below does not compile:
//mikael.name = "Nicolas"
// you need to create a new instance using copy
val nicolas = mikael.copy(name = "Nicolas")

In the preceding code, the text following // is a comment that explains the preceding statement.

When you declare a class as case class, the Scala compiler automatically generates a default constructor, an equals and hashCode method, a copy constructor, and an accessor for each attribute.

Here is a screenshot of the worksheet we have. You can see the results of the evaluations on the right-hand side: