rspec/rules/S6218/kotlin/rule.adoc

== Why is this an issue?

In data classes, the default behavior of the `equals()` method is to check the equality by field values. This works well for primitive fields or fields, whose type overrides `equals()`, but this behavior doesn't work as expected for array fields.


By default, array fields are compared by their reference, so overriding `equals()` is highly recommended to ensure a deep equality check. The same applies to the `hashcode()` method.


This rule reports an issue if a record class has an array field and is not overriding `equals()` or `hashcode()` methods.


=== Noncompliant code example

[source,kotlin]
----
data class Person(val names: Array<String>, val age: Int) {} // Noncompliant
----


=== Compliant solution

[source,kotlin]
----
data class Person(val names: Array<String>, val age: Int) {
    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (javaClass != other?.javaClass) return false

        other as Person

        if (!names.contentEquals(other.names)) return false
        if (age != other.age) return false

        return true
    }

    override fun hashCode(): Int {
        var result = names.contentHashCode()
        result = 31 * result + age
        return result
    }
}
----