How to create a new object from data class

Question

I have a data class which extends another abstract class.

data class Savings(
  val amount: BigDecimal? = null
) : Account()

abstract class Account(
  val accountNumber: BigDecimal? = null
)

val saving: Savings = Savings(amount = BigDecimal.ONE)

How can I set the value for accountNumber property as that is not available in constructor. What other way I can set the value of the field?

reddit.com/r/Kotlin/comments/o7q9fc/…

firstpostcommenter
– firstpostcommenter

2022-03-15 15:59:16 +00:00
Commented Mar 15, 2022 at 15:59 — firstpostcommenter
– firstpostcommenter, Commented Mar 15, 2022 at 15:59
reddit.com/r/Kotlin/comments/6s7uia/…

firstpostcommenter
– firstpostcommenter

2022-03-15 20:32:20 +00:00
Commented Mar 15, 2022 at 20:32 — firstpostcommenter
– firstpostcommenter, Commented Mar 15, 2022 at 20:32

Tenfour04 · Accepted Answer · 2022-03-15 16:47:16Z

1

You can make the property open in the superclass so you can override it in the data class constructor:

data class Savings(
  val amount: BigDecimal? = null,
  override val accountNumber: BigDecimal?
) : Account()

abstract class Account(
  open val accountNumber: BigDecimal? = null
)

answered Mar 15, 2022 at 16:47

Tenfour04

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2 Comments

firstpostcommenter Over a year ago

So this needs to be done for all fields. Now I wonder if there is any point in creating abstract class with so much code duplication in Kotlin

Tenfour04 Over a year ago

I guess that would be true if the only reason you want to use an abstract class is to reduce the amount of code. It’s a shortcoming with data classes. It might be easier to define a standard class and use IDE features to generate equals and hashcode for you. Data classes are meant for simple data containers so it is not often that it makes sense for it to be a subclass of something.

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