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asked in CSC285_Fall2018 by (3.7k points)

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Short version: Aggregation and composition are both special types of "association". They both represent whole/part relationships, but composition is "stronger", in the sense that if you removed the whole, then all of the part objects should disappear as well.

If a Person class has two Hand objects that are part of it, that's presumably composition, since the Hands shouldn't exist without the person.

If a SoccerTeam object contains a bunch of Player objects, then that could be aggregation, since a team is made up of players, but those individual players could still exist (e.g. maybe join other teams) even if the SoccerTeam gets disbanded.

Longer version: https://www.visual-paradigm.com/guide/uml-unified-modeling-language/uml-aggregation-vs-composition/

Note: I won't expect you to make this subtle distinction on the exam.

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