Question

Java Programming Exercise:

Creating and implementing a UML class diagram

The inventory of a library is a set of media. Media can be books, CDs and films. Each medium has a unique alphanumeric ID, a title, a year of publication and the date on which it was purchased. Each book also has an author and an ISBN. For each CD the artist and the number of titles are saved. Each movie has a genre and a format: either DVD or Blu-ray. There is a getter for each attribute. Every medium of every kind should be able to be converted into a string with toString; all attribute values ​​should appear in the returned string. Changes to the stock of the library are not planned. The library should each have a method for the following functionalities:

• All old media should be able to be output on the console. A book is considered old if it appeared before 1970. A CD is considered old if it was released before 1995. A movie is considered old if it was released before 2000.

• All Blu-rays should be able to be output on the console.

• All media should be able to be played on the console whose title is not unique, i. there is another medium with the same title. Example: A movie and a book of the same title.

• All media should be output in the order of purchase on the console.

a) Create a UML class diagram for the above description. Not all information is relevant to the chart, but some just for the implementation. You may add other classes and methods, as appropriate.

Answer 1

Description:

Class diagrams comes in structural UML diagrams. Class diagram gives the static view of the system, i.e. it emphasizes on what rather than how. For eg: for a given media, we can describe an ID for it, and a method getID(). It doesn't consider how getID() is implemented, or how ID is stored in database.

In the given diagram:

+ : denotes public variables/methods.

- : denotes private variables/methods.

# : denotes protected variables/methods.

Overview:

1. The media can be built as a parent class, and can be kept abstract. The 3 classes: movie, books and CD are derived from it.

2. There is a separate class that implements 4 cases given above. This class can be associated with the media class.

3. The media class shares 0..* relationship with it's child classes (books, CD and movie) i.e. there are minimum 0 objects and maximum as many objects as possible of that particular type.

The diagram can be found in the attached figure: