GoGreen Bikes - Identify attributes of and relationships between classes

While identifying relationships, I realised that I need 2 more classes - a list of customers and a list of bikes. The reasoning behind this will be explained in the data dictionary.

Once I had decided on which classes I would have, I printed and cut them out so that each class was on a small paper rectangle. Then I could move them around while working out the relationships between them.

Multiplicities

There are zero or more bikes on the bike list but there is only one bike list.

A hire transaction must have one and only one bike associated with it, but a bike has either zero (not currently hired) or one (currently hired) transaction associated with it.

A customer hires zero or more bikes (multiple hires possible), but a bike has either one (hired) or zero (not hired) customers associated with it.

A customer is associated with zero or more hire transactions (multiple hires possible) but a hire transaction may only have one customer associated with it.

There are zero or more customers on the customer list but there is only one customer list.