### Relationships (contd..)

• Describe Object Oriented stuff diagrammatically we use UML (Unified Modelling Language)
• I have oranges and i can place oranges in a basket
• Orange is an object
• There is a relationship b/w basket and oranges
• To represent in basic class diagram
• When we specify a relationship b/w oranges and basket it is many oranges in one basket (many to one)
• Now lets try cardinality between bus and a conductor
• Line between two classes is association & numbers at the end of the line represent cardinality
• Sample class diagram looks like (note this is not completely correct version)

#### Lets try to design objects and their relationships in a library.

• This library has
• Books
• DVDs
• Magazines
• CDs
• The user are librarian and readers. Librarian gives a unique number (lib_id)
• Librarian needs to locate the library items
• Readers will also be given catalog where they can search for existence of book or not
• Lets think of different classes
• Book
• DVD
• Magazine
• CD
• Shelf
• Catalog
• Now lets speak normal english to come up with design
• Book is a LibraryItem
• DVD is a LibraryItem
• Magazine is a LibraryItem
• CD is a LibraryItem
• Shelf has LibraryItem’s
• Now the diagrammatic representation will be something like

### Exercise:

• Create a diagram as shown above for the following problem statement
• A Bank has a savings account, fixed deposit account, recurring deposit account and loan accounts
• Bank Manager/Accountant would like to search with an account number using Account Console
• Customers should be able to see account balance, last transactions
• Also represent Transactions in the diagram.

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