--- title: "OOPS Design concepts - difference between association and aggregation" description: "OOPS Design concepts - difference between association and aggregation" author: "marcel ethan" published: 2015-10-05 updated: 2015-10-05 canonical: https://www.mindstick.com/forum/33492/oops-design-concepts-difference-between-association-and-aggregation category: "java" tags: ["c#", "java", "oops"] reading_time: 1 minute --- # OOPS Design concepts - difference between association and aggregation I am pretty confused about [oops](https://www.mindstick.com/articles/1558/introduction-to-oops-object-oriented-programming-system) [design principles](https://www.mindstick.com/forum/157670/explain-the-design-principles-of-security-in-os). In [UML](https://www.mindstick.com/forum/33493/oops-design-principles-what-is-uml-what-is-the-need-of-uml) [class diagram](https://www.mindstick.com/articles/12168/unified-modeling-language) there are notations of association and aggregation. I want to undersatnd what is the exact [difference](https://www.mindstick.com/articles/157114/good-news-or-bad-news-and-the-difference-is) between these two, because according to me these are very similar and used for same [purpose](https://yourviews.mindstick.com/view/247/no-fail-policy-failing-its-purpose) ## Replies ### Reply by Anonymous User **Association** is a relationship between two objects. In other words, association defines the multiplicity between objects. You may be aware of one-to-one, one-to-many, many-to-one, many-to-many all these words define an association between objects. Aggregation is a special form of association. Composition is a special form of aggregation. ***Example*** : A Student and a Faculty are having an association.\ **Aggregation** is a special case of association. A directional association between objects. When an object ‘has-a’ another object, then you have got an aggregation between them. Direction between them specified which object contains the other object. Aggregation is also called a “Has-a” relationship\ Example : (City, Tree, Car) "sub objects" (Tree, Car) will NOT be destroyed when City is destroyed. --- Original Source: https://www.mindstick.com/forum/33492/oops-design-concepts-difference-between-association-and-aggregation Copyright © MindStick Software Pvt. Ltd. This Markdown version is provided for developers, AI systems, and offline reading.