Clone Standard Signature

ID

java.clone_standard_signature

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

Java

Tags

clone, reliability

Description

Reports clone() methods with non-standard return types. The clone() method must return Object (or a covariant subtype), never void.

Rationale

A void clone() method cannot be used by the Cloneable mechanism and confuses callers who expect a copy to be returned.

// Bad \u2014 void return
public void clone() throws CloneNotSupportedException {
    // cannot return a copy
}

Remediation

Return Object (or the class type via covariant return):

// Good
public Object clone() throws CloneNotSupportedException {
    return super.clone();
}

References