There is the following example in <https://play.ko...

# getting-started

[Paul at Avans Breda]

There is the following example in https://play.kotlinlang.org/byExample/overview for Kotlin Data classes: https://play.kotlinlang.org/byExample/03_special_classes/01_Data%20classes

It seems to me that this example violates the principle that when overriding the equals method you should also override the hashCode(). I'm I missing something?

[Ronny Bräunlich]

Not necessarily. hashCode is overwritten due to data classes' characteristics. The difference is, that in the example equals() is based solely on id and hashCode uses name and id, both.

[Paul at Avans Breda]

But in this example it is possible that two objects are equal (using the overridden equals() method) but have a different hashCode.

Am I correct that this violates the contract between equals() and hashCode(): objects that are equal to each other must return the same hashCode

[Ronny Bräunlich]

That's correct. It violates:
_equals consistency_: objects that are equal to each other must return the same hashCode

[Paul at Avans Breda]

For an example that is looked upon by many students learning the Kotlin language this is confusing.