Omit optional parameters set as null in Kotlin data class

Question

Best practice to omit optional parameter in a data class when its assigned null?

Example: data class xyz(val a:String ?,val b: String?, val c: String?= null) if c = null, then data class xyz(val a:String ?,val b: String?).

Calling xyz.toString() which takes null as "null". So output is xyz("String for a", String for b", "null").

But actual output xyz("String for a", String for b").

Can I use secondary constructor or invoke() ? Which is better?

It's not entirely clear for me what you mean. Omit optional parameters when doing what exactly? When creating an object, when printing it in toString()? If the latter, how would you like to distinguish cases when cis null and b is null (assuming it is optional as well)? Both these cases would produce exactly same output. You can always implement toString() by yourself. — broot
– broot, Commented Aug 31, 2023 at 23:54

ryankuck · Accepted Answer · 2023-08-31 22:38:13Z

0

If you sometimes need a value c but not in this case, then the two options are:

val newXyzObject = xyz(a = "String for a", b = "String for b", c = null)

or

val newXyzObject = xyz(a = "String for a", b = "String for b")

but since c has a default value it is preferred to go with the second option because it is more readable.

answered Aug 31, 2023 at 22:38

ryankuck

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