45 Class inheritance

NamedCounter extends Counter keeps the base fields and adds name. Its constructor calls super(initial: initial) before assigning the new field.

class Counter {
  Integer value

  Counter(Integer initial) { value = initial }
}

class NamedCounter extends Counter {
  String name

  NamedCounter(Integer initial, String name) {
    super(initial: initial)
    this.name = name
  }
}

main() {
  NamedCounter counter = NamedCounter(initial: 3, name: "visits")
  printLine("${counter.name}: ${counter.value}")
}

Expected output:

visits: 3

Try it: Change the initial count and verify the inherited value.

Precise rules: Reference.