Association Implementation

Before starting this lab, you must read the section Implémentation d’associations.

Use Java to implement three UML association between the class fr.unantes.software.construction.associations.Event and the classes Contact, Task, and Calendar. Use the Wrapper implementation strategy introduced during the lectures.

Open the Maven module named associations. Part of the implementation is already done:

  • There are several unit tests to ensure the correctness of your implementation.

  • There are also 1 java interface implementation for each UML class.

  • There are also two java interfaces to help you implement the associations: SingleReference and MultipleReference.

  • For executing the JUnit tests for this lab, execute the following command in the project root folder:

mvn package -PAssociations

1. Association between Event and Contact

Start with the simpler association. The association between Event and Contact is unidirectional, all you have to do is to implement the interface MultipleReference, in order to contain several contacts.

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2. Association between Event and Task

This association is bidirectional and therefore harder to implement. Your code must ensure the handshake (referential integrity).

You will have to implement the interface SingleReference twice: from Event to Task and from Task to Event

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  • Start with the simpler case: a new event (evt1) and a new task (task1). Ensure that setting the event of task1 to evt1 is equivalent to setting the task of evt1 to task1.

  • Afterwards, take a harder case: a first event (evt1) is related to a task (task1) and a second event (evt2) is related to a second task (task2). Ensure that is you set the task of evt1 to task2 (or vice versa):

    • evt2 will not be related to any task and

    • taks1 will not be related to any event.

3. Association between Event and Calendar

This last association is also the most complex. The association between Event and Calendar is also bidirectional, but in this case, one of the references is multi-valued and must implement the interface MultipleReference.

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4. Conclusion

Once all the tests pass, your are done: now you know how to implement UML associations.

Before packing up your things, let us have some thought: you implemented the same interfaces (SingleReference and MultipleReference) several times: is it possible to generalize your code and use the same class for different mono-valued references and the same class for different multi-valued references?