hello, i have a question related to pojos and how ...

# announcements

[Andreas Unterweger]

hello, i have a question related to pojos and how to create them in kotlin with data classes.
we have a bean which gets successively filled with data in different methods. this bean has other beans nested. if i use val in data classes this seems to become an issue since i cannot reassign vals. on the other hand i want to avoid nullability. so i want to set a default value and later overwrite it. is there a pattern in kotlin for that?

[sanatik]

https://kotlinlang.org/docs/reference/properties.html#late-initialized-properties-and-variables
This should do the trick

[Ubi]

snippet.kt

snippet.kt

[Ubi]

val is immutable. you need to use var

[Can Orhan]

Hmm. I’d probably be hesitant doing either of those recommendations. Not sure what your code is like but maybe the builder pattern could be applicable if you want to keep your model atomic? Contributing functions would contribute to a builder’s set function. The use site would receive the builder.build()

[Andreas Unterweger]

i dont think this works, because it would have to be created at the same time, no?

[Andreas Unterweger]

i guess the var or lateinit approach are fine

[Ubi]

If you are using a data class then lateinit won’t work for you. I also don’t think builder pattern solves your issue.

[Ubi]

https://kotlinlang.org/docs/reference/data-classes.html

In case you want to keep the objects immutable than you can use copy

[Andreas Unterweger]

but copy seems bad; assume i want to change one val field in a nested bean...that would not look nice. i guess ur proposal for vars with default values makes most sense. i loose immutability but i still have non nullability