What is the Difference Between Aggregation and Composition in Java?

In Java, aggregation and composition are two forms of association between classes. They are related to the "has-a" relationship, but they have different characteristics:

Aggregation:

• It is a weak association, meaning that the associated objects can exist independently of each other.
• It represents a "Has-A" relationship, where one class instance can have multiple instances of another class.
• Aggregation is a unidirectional association, i.e., a one-way relationship.
• In aggregation, objects are not tightly coupled or don't involve owning.

Composition:

• It is a strong association, meaning that the associated objects are highly dependent on each other.
• It represents a "part-of" or "belongs-to" relationship, where one class instance is composed of another class instance.
• In composition, both entities are dependent on each other, and the composed object cannot exist without the other entity.
• Composition is a restricted form of aggregation.

In summary, aggregation is a weak association where the associated objects can exist independently, while composition is a strong association where the associated objects are highly dependent on each other.

Comparative Table: Aggregation vs Composition in Java

The main difference between aggregation and composition in Java is the ownership of the second object. Here is a table summarizing the differences between aggregation and composition:

Both aggregation and composition are used to represent relationships between objects in Java, but they serve different purposes and have distinct characteristics. By understanding these differences, you can make more informed decisions when designing and implementing your classes.