---
title: "Parallel Inheritance Hierarchies"
type: "code-smell"
slug: "parallel-inheritance-hierarchies"
url: "http://localhost:3000/en/smells/parallel-inheritance-hierarchies.md"
category: "Change Preventers"
description: "Whenever you create a subclass for a class, you find yourself needing to create a subclass for another class."
---
# Parallel Inheritance Hierarchies

> Whenever you create a subclass for a class, you find yourself needing to create a subclass for another class.

## Signs and Symptoms

Whenever you create a subclass for a class, you find yourself needing to create a subclass for another class.

## Reasons for the Problem

All was well as long as the hierarchy stayed small. But with new classes being added, making changes has become harder and harder.

## Payoff

* Reduces code duplication.
* Can improve organization of code.
## Relations

**Treated by**

- [Move Method](/en/move-method.md)
- [Move Field](/en/move-field.md)