Review the Class Diagram Notation

Classes are modeled using

1. a single rectangular shape with
2. three internal compartments: name, attribute, and operation.

• Name compartment The name compartment holds 1) the class name, 2) an optional stereotype, and 3)optional properties. The name is located in the center of the compartment. The stereotype (<< >>) may be used to limit the role of the class in the model, and is placed at the top of the compartment. Common examples of class stereotypes include <<Factory>>, based on the Factory design pattern, and <<Interface>>, for Java interfaces or for user interfaces. Properties use the constraint notation and are placed in the bottom-right corner of the compartment. Properties are basically constraints, used to clarify intent in defining the model element. Properties can be used to document the status of a class under development or for designations such as abstract and concrete.

• Attribute Compartment: The attribute compartment simply lists the attributes of the class using the notation you learned previously. The list order does not matter.
  

  

• Operation Compartment
  Likewise, operations are listed in the operation compartment using the notation you learned in the first course in this series.
  

  

The completed class definition can be shown either as the entire class definition with all three compartments visible or as just the name compartment.

Many tools also support different views of the operations, for example, name, argument data types, and return data type only, or with fully expanded arguments.

The UML supports user-defined compartments as well. You can define virtually any type of information to append to a class by creating additional compartments. At this time, I am unaware of any tools that allow you to take advantage of this feature.

A graphical subdivision of a closed symbol, such as a class rectangle divided vertically into smaller rectangles. Each compartment shows properties of the element that it represents. Compartments come in three kinds: fixed, lists, and regions.
Notation:
A fixed compartment has a fixed format of graphical and text parts to represent a fixed set of properties. The format depends on the kind of element. An example is a class name compartment, which contains a

1. stereotype symbol and/or name,
2. a class name, and
3. a property string

that shows various class properties. Depending on the element, some of the information may be suppressible.
A list compartment contains a list of strings that encode constituents of the element. An example is an attribute list, where the encoding depends on the constituent type. The list elements may be shown in their natural order within the model, or they may be sorted by one or more of their properties (in which case, the natural order will not be visible). For example, a list of attributes could be sorted first on visibility and then on name. List entries can be displayed or suppressed based on the properties of the model elements. An attribute compartment, for instance, might show only public attributes. Stereotypes and keywords may be applied to individual entries by prepending them to the list entry. A stereotype or keyword may be applied to all subsequent entries by inserting it as a list entry by itself. They affect all subsequent list entries until the end of the list or another such running declaration. The string <<constructor>> placed on a separate line in an operation list would stereotype the subsequent operations as constructors, but the string «query» further down the list would revoke the first declaration and replace it by the <<quer>> stereotype.

The three parts of the class diagram notation are described below

The sample program is very simple. It is a program to calculate and print a statement of a customer's charges at a video store. The program is told which movies a customer rented and for how long. It then calculates the charges, which depend on how long the movie is rented, and identifies the type movie. There are three kinds of movies: regular, children's, and new releases. In addition to calculating charges, the statement also computes frequent renter points, which vary depending on whether the film is a new release.
Several classes represent various video elements. Here's a class diagram to show them (Figure 2.6).

I will show the code for each of these classes in turn.
Movie: Movie is just a simple data class.

public class Movie {
public static final int CHILDRENS = 2;
public static final int REGULAR = 0;
public static final int NEW_RELEASE = 1;
private String _title;
private int _priceCode;
public Movie(String title, int priceCode) {
_title = title;
_priceCode = priceCode;
}
public int getPriceCode() {
return _priceCode;
}
public void setPriceCode(int arg) {
_priceCode = arg;
}
public String getTitle (){
return _title;
};
}

Rental: The rental class represents a customer renting a movie.

class Rental {
private Movie _movie;
private int _daysRented;
public Rental(Movie movie, int daysRented) {
_movie = movie;
_daysRented = daysRented;
}
public int getDaysRented() {
return _daysRented;
}
public Movie getMovie() {
return _movie;
}
}

Customer: The customer class represents the customer of the store. Like the other classes it has data and accessors:

class Customer {
private String _name;
private Vector _rentals = new Vector();
public Customer (String name){
_name = name;
};
public void addRental(Rental arg) {
_rentals.addElement(arg);
}
public String getName (){
return _name;
};

1. Name compartment
2. Attribute compartment
3. Operation compartment
4. Class name
5. Properties
6. Stereotype