The JEP states this:
Restrictions on records
Records cannot extend any other class, and cannot declare instance fields other than the private final fields which correspond to components of the state description. Any other fields which are declared must be static. These restrictions ensure that the state description alone defines the representation.
The Java 17 JLS 8.10 notes1 this:
A
record
declaration does not have anextends
clause, so it is not possible to explicitly declare a direct superclass type, evenRecord
.
However, a record
can implement
interfaces, so you can use them polymorphically. Furthermore, since records will inherit any default
methods in the interfaces that they implement, they do support a limited form of inheritance.
1 – This is a non-normative statement, but it is obviously true since the specified syntax for RecordDeclaration clearly does not allow extends
to be used.