What is the difference between association, aggregation and composition?

Question

What is the difference between association, aggregation, and composition? Please explain in terms of implementation.

Answer 1

From: Remo H. Jansen book “Beginning React: Learning TypeScript 2.x - Second Edition” :

We call association those relationships whose objects have an independent life cycle where there is no ownership of the objects. Let's take a look at an example of a teacher and a student. Multiple students can be associated with a single teacher, and a single student can be associated with multiple teachers, but both have independent life cycles (both can create and delete independently). So, when a teacher leaves the school, we don't need to delete any students, and when a student leaves the school, we don't need to delete any teachers.

We call aggregation those relationships whose objects have an independent life cycle, but there is ownership, and child objects cannot belong to another parent object. Let's take an example of a cell phone and a cell phone battery. A single battery can belong to a phone, but if the phone stops working, and we delete it from our database, the phone battery will not be deleted because it may still be functional. So, in aggregation, while there is ownership, objects have their life cycle

We use the term composition to refer to relationships whose objects don't have an independent life cycle, and if the parent object is deleted, all child objects will also be deleted. Let's take an example of the relationship between questions and answers. Single questions can have multiple answers, and answers cannot belong to multiple questions. If we delete questions, answers will automatically be deleted.