I built a small Java program to practice inheritance — looking for feedback

[u/Few_Strain_8521]

I'm currently learning Java and recently practiced inheritance by creating a simple example with a Person parent class and Student child class.

I understand the basic concept, but I'm still trying to understand when inheritance is actually useful in a real project rather than just using it because the language allows it.

For people who use Java professionally, what are some situations where inheritance makes sense, and when would you choose composition instead?

I'm interested in understanding the reasoning behind the design choice, not just the syntax.

[u/Educational-Paper-75]

Use inheritance when the relationship is an IS A relationship and composition in a HAS A relationship. A car HAS an engine, a human IS a mammal IS an animal.

[u/Few_Strain_8521 → u/Educational-Paper-75]

Nice thank you for explanation

[u/HyperDanon → u/Few_Strain_8521]

@Few_Strain_8521 If I can suggest you something, please don't follow this advise. It doesn't really help design good software. This isn't really a proper thing to do. Relationships from the real world don't transfer to relationships in software; certainly not as a rule.

Inheritance isn't "is-a" relationship, it's just a rather tight coupling between two classes, for the purpose of reuse and substituion, nothing more. More often than not, you should use composition for reuse, and interfaces for polimorphism.

Myself, I only use inheritance when there is a clear hierarchy of objects, such as in UI library.

[u/No_Assignment9285]

I'll give you an example in the world of web development. Suppose you want to create multiple DB tables that uses the columns updated at, created at, then create a super class and inherit that for the classes that creates the DB tables. Simple?

[u/Few_Strain_8521 → u/No_Assignment9285]

Yup bro understood

[u/Ollidav]

Persona es una idea abstracta ya que podemos saber que hablamos de personas pero no podemos concretar que persona es ya que, aunque todas tienen atributos en común, unas pueden ser altas, calvas o con diferente color de piel u ojos. La idea de herencia sería que quiero trabajar con Persona que tiene unos atributos como altura, color de pelo, ojos y puede andar hacia delante o atrás, saltar, tumbarse, etc... pero durante el desarrollo voy a necesitar diferentes tipos de personas. Muchas de esas personas compartirán atributos como el de saltar, caminar o tumbarse pero tendrán un diferente color de pelo, altura, peso o velocidad al moverse.

[u/habrem]

So if IS A works so well why is every Java codebase Ive touched full of @Component and interfaces instead of extends

[u/MentalAnteater1286]

Inheritance makes sense when the child truly is a specialized version of the parent. composition is usually better when you just want to reuse behavior

[u/Inevitable_Leg5543]

Inheritance makes sense when the child truly is a specialized version of the parent. composition is usually better when you just want to reuse behavior