A clone method that is overridden in a subclass should call super.clone. Not doing so causes the subclass clone to return an object of the wrong type, which violates the contract for Cloneable.

Every clone method should always use super.clone to construct the cloned object. This ensures that the cloned object is ultimately constructed by Object.clone, which uses reflection to ensure that an object of the correct runtime type is created.

In the following example, the attempt to clone WrongEmployee fails because super.clone is implemented incorrectly in its superclass WrongPerson.

However, in the following modified example, the attempt to clone Employee succeeds because super.clone is implemented correctly in its superclass Person.
  • J. Bloch, Effective Java (second edition), Item 11. Addison-Wesley, 2008.
  • Java API Specification: Object.clone().