Why is Java's `clone()` Method Protected and Not Part of the `Cloneable` Interface?

Protected Clone() Method in Java: A Puzzling Decision

Java's clone() is a peculiar method, protected within java.lang.Object. Why this perplexing decision?

Inability to Leverage Cloneable Interface

Unlike other frameworks where copyable classes implement a cloneable interface, Java's clone() is not declared in Cloneable. Consequently, checking for cloneability using the interface is impossible. Code like "if(a instanceof Cloneable)" cannot determine if 'a' supports cloning.

Reflection Dependency

To bypass this limitation, reflection can be employed. However, this approach introduces unnecessary complexity and relies on knowledge of concrete class implementations. It also relies on a strict protocol, often undocumented and unenforceable.

Regretful Design

Josh Bloch, author of Effective Java, labels Cloneable's design "a mistake." It fails to effectively advertise cloning support and imposes a cumbersome protocol. Instead, he suggests implementing Cloneable at the class level, ensuring compliance with the protocol.

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