rspec/rules/S6218/java/rule.adoc

== Why is this an issue?

In records, 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, and overriding ``++equals()++`` is highly appreciated to achieve the deep equality check. The same strategy applies to ``++hashcode()++`` and ``++toString()++`` methods.


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


=== Noncompliant code example

[source,java]
----
record Person(String[] names, int age) {} // Noncompliant
----


=== Compliant solution

[source,java]
----
record Person(String[] names, int age) {
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Person person = (Person) o;
        return age == person.age && Arrays.equals(names, person.names);
    }

    @Override
    public int hashCode() {
        int result = Objects.hash(age);
        result = 31 * result + Arrays.hashCode(names);
        return result;
    }

    @Override
    public String toString() {
        return "Person{" +
                "names=" + Arrays.toString(names) +
                ", age=" + age +
                '}';
    }
}
----


== Resources

* https://docs.oracle.com/javase/specs/jls/se16/html/jls-8.html#jls-8.10[Records specification]

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Override [equals|hashcode|toString] to consider array's content in the method


=== Highlighting

record declaration


endif::env-github,rspecator-view[]