Скачать или смотреть Creating a Doubly Linked List from a Basic Linked List: Composition vs Inheritance

Discover the best approach to create a `Doubly Linked List` from a Basic Linked List by understanding the concepts of composition and inheritance in Java.
---
This video is based on the question https://stackoverflow.com/q/63421783/ asked by the user 'HelloWorld' ( https://stackoverflow.com/u/13748491/ ) and on the answer https://stackoverflow.com/a/63421839/ provided by the user 'Tarik' ( https://stackoverflow.com/u/990750/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Creating doubly linked list(DLL) from a basic linked list-Composition or inheritance?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Creating a Doubly Linked List from a Basic Linked List: Composition vs Inheritance

When working with data structures, one of the common challenges you might face is deciding how to extend or modify existing structures. A question many developers encounter is how to effectively create a Doubly Linked List (DLL) from a Basic Linked List (BLL). This decision often comes down to two fundamental design principles: composition and inheritance.

In this post, we'll explore the distinctions between these two approaches and determine the most appropriate method for constructing a DLL from a BLL.

Understanding the Basic Linked List

Before diving into the solution, it's essential to have a brief understanding of what we are working with. A Basic Linked List (BLL) provides core functionalities like:

Insertions at:

The head

The tail

Any position in between

Deletions from:

The head

The tail

Any position in between

These operations allow for a flexible and dynamic way to manage data.

The Dilemma: Composition vs Inheritance

When considering the construction of a DLL from a BLL, the question arises whether to use composition or inheritance.

Composition

Composition is a design principle that implies a "has-a" relationship. It allows you to build complex types by combining objects. The challenge with applying composition in this scenario is how to introduce a pointer to the previous node while ensuring functionality:

Pros:

Promotes code reusability

Reduces dependencies between classes

Cons:

Complexity in managing the pointers (especially for a DLL)

Inheritance

In contrast, inheritance embodies an "is-a" relationship, which allows one class to inherit the properties and behaviors of another. Using inheritance to create a DLL from a BLL provides direct access to the methods and variables of the BLL.

Pros:

Simplicity in accessing parent class methods and properties

Ease of extending functionality

Cons:

Can lead to tighter coupling between classes

Possible difficulties in future maintenance if the parent class changes

The Conclusion: Inheritance Is the Preferred Approach

After considering both options, it's crucial to acknowledge that the advice of "favor composition over inheritance" does not imply that inheritance should be avoided entirely. In this specific case, due to the need for accessing core operations from the BLL, inheritance is the more fitting approach.

Why Inheritance Works Here

Access to BLL's Core Methods: Since a DLL inherently requires functionalities of a BLL, inheriting methods such as insert and delete simplifies the implementation.

Less Complexity: Managing previous node pointers is simpler when using inheritance, as you can directly manipulate BLL attributes and methods without the overhead of managing separate objects.

Alignment with Liskov Substitution Principle: By using inheritance, you ensure that the DLL can be substituted for the BLL whenever necessary, fulfilling the Liskov Substitution Principle (LSP).

Final Thoughts

Choosing between composition and inheritance is a fundamental design decision in software engineering. For creating a Doubly Linked List from a Basic Linked List, inheritance provides a more straightforward and effective means of extending functionality. By leveraging the existing methods of the BLL, you can seamlessly incorporate the additional features of a DLL with minimal complexity.

Embrace inheritance where it fits the problem — it could very well be the key to simplifying your data structure implementations!