Class diagram - Android app for dog owners

Question

I am struggling how to model the class diagram. I am confused with bindings. Users can create a new dog. When the user is removed also reminders, dogs should be deleted. Isnt it composition? Memories are related to dogs, they should be deleted when the dog is deleted too. Could you help with the bindings?

Answer 1

You are absolutely right with your assumption. A composite aggregation is shown by a filled diamond towards the aggregating class. And it's intended use is like you need it (forgot to include multiplicities):

As a side note:

• your FireBaseApplication seems to be way off. There shouldn't be any class specific methods like removeDogCascade but only a removeCascaded where you can supply a class that has aggregate relations.
• between User and Dog you should use a role name owner towards User to identify the dog's owner, rather than having a String property with the user's name (or whatever that might contain)
• Similarly between Dog and Memory