Final Parameter on Abstract Method

ID

java.final_param_on_abstract_method

Severity

info

Remediation Complexity

medium

Remediation Risk

low

Remediation Effort

medium

Resource

Code smell

Language

Java

Tags

code-style

Description

Reports final parameters declared on abstract methods or interface methods without a default body. The final modifier prevents reassignment of a parameter within a method body, but abstract and bodiless interface methods have no body, so final has no effect.

Rationale

Marking a parameter final on an abstract method is misleading because it suggests that implementations must honor the constraint, but Java does not enforce this. Each implementing class is free to declare its parameter as final or not, regardless of the abstract declaration:

// Bad - final has no effect on abstract method
public abstract class Processor {
    public abstract void process(final String input);
}

// Bad - final has no effect on interface method
public interface Handler {
    void handle(final int code, final String message);
}

Remediation

Remove the final modifier from abstract and interface method parameters:

// Good - no misleading final
public abstract class Processor {
    public abstract void process(String input);
}

// Good
public interface Handler {
    void handle(int code, String message);
}

References