Unnecessary Default Constructor

ID

java.unnecessary_default_constructor

Severity

low

Remediation Complexity

medium

Remediation Risk

low

Remediation Effort

medium

Resource

Code Smell

Language

Java

Tags

code-style

Description

Reports classes with a single explicit no-argument constructor whose body is empty. Java automatically provides a default no-arg constructor when no constructors are declared, so the explicit one is redundant.

Rationale

An empty public no-arg constructor adds boilerplate without changing behavior. Removing it reduces noise and makes the code cleaner. If the intent is to document the constructor or to have a specific access modifier, a comment or a non-empty body makes the purpose clear.

// Bad -- redundant constructor
public class MyService {
    public MyService() {
    }

    public void process() { }
}

// Good -- no explicit constructor needed
public class MyService {
    public void process() { }
}

Remediation

Remove the empty no-arg constructor. If a specific access modifier is needed (e.g., private for utility classes), keep it but that is a different intent.

References