The class is the dominant model element on a class diagram. In
the UML metamodel it is a sub-class of
Classifier
and
GeneralizableElement
.
A class is represented on a class diagram as a rectangle with three compartments. The top compartment displays the class name (and stereotypes), the second compartment any attributes and the third any operations. These last two compartments may optionally be hidden.
The details tabs that are active for classes are as follows.
ToDoItem
Standard tab.
Properties
See Section 18.6.2, “ Class Property Toolbar ” and Section 18.6.3, “ Property Fields For Class ” below.
Documentation
Standard tab. See Section 13.4, “ Documentation Tab ”.
Presentation
Standard tab. The tick boxes,
Attributes
and Operations
allow the attributes and operations compartments to be
shown (the default) or hidden. This is a setting valid
for only the current diagram that shows the class. The
editable
Bounds
field defines the bounding
box for the package on the diagram.
Source
Standard tab. This contains a template for the class declaration and declarations of associated classes.
Constraints
Standard tab. There are no standard constraints
defined for Class
within the UML
metamodel.
Stereotypes
Standard tab.
Tagged Values
Standard tab. In the UML metamodel,
Class
has the following standard tagged
values defined.
persistence
(from the
superclass, Classifier
). Values
transitory
, indicating state is
destroyed when an instance is destroyed or
persistent
, marking state is preserved
when an instance is destroyed.
semantics
(from the
superclass, Classifier
). The
value is a specification of the semantics of the
class.
derived
(from the
superclass, ModelElement
).
Values true
, meaning the class
is redundant -it can be formally derived from other
elements, or false
meaning it
cannot.
![]() | Note |
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Derived classes still have their value in analysis to introduce useful names or concepts, and in design to avoid re-computation. |
![]() | Note |
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The UML |
Checklist
Standard tab for a Classifier.
Go up
Navigate up through the package structure.
New attribute
This creates a new attribute (see Section 18.7, “ Attribute ”) within the class, navigating immediately to the properties tab for that attribute.
New operation
This creates a new operation (see Section 18.8, “ Operation ”) within the class, navigating immediately to the properties tab for that operation.
New reception
This creates a new reception, navigating immediately to the properties tab for that reception.
New inner class
This creates a new inner class (which appears on no diagram) within the class. This belongs to the class and is restricted to the namespace of the class. It exactly models the Java concept of inner class. As an inner class it needs no attributes or operations, since it shares those of its owner.
![]() | Note |
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Inner class is not a separate concept in UML. This is a convenient shorthand for creating a class that is restricted to the namespace of its owning class. |
New class
This creates a new class (which appears on no diagram) within the same namespace as the current class.
New Stereotype
This creates a new Stereotype (see Section 16.6, “ Stereotype ”) for the selected class, navigating immediately to the properties tab for that stereotype.
Delete
This deletes the class from the model
![]() | Warning |
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This is a deletion from the model
not just the diagram. To delete
a class from the diagram, but keep it within the
model, use the main menu |
Name
Text box. The name of the class. The name of a class has a leading capital letter, with words separated by “bumpy caps”.
![]() | Note |
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The ArgoUML critics will complain about class names that do not have an initial capital. |
Namespace
Drop down selector with navigation button. Records and allows setting of the namespace for the class. This is the package hierarchy.
Button 1 click on the entry will move the class to the selected namespace.
Modifiers
Check box, with entries
Abstract
, Leaf
,
Root
, and Active
.
Abstract
is used to
declare that this class cannot be instantiated, but
must always be subclassed. The name of an abstract
class is displayed in italics on the diagram.
![]() | Caution |
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If a class has any abstract operations, then it should be declared abstract. ArgoUML will not enforce this. |
Leaf
indicates that this
class cannot be further subclassed, while
Root
indicates it can have no superclass.
It is possible for a class to be both Abstract and
Leaf, since its static operations may still be
referenced.
Active
indicates that this
class exhibits dynamic behavior (and is thus
associated with a state or activity diagram).
Visibility
Radio box, with four entries
public
, private
,
protected
, and
package
. Indicates whether the
class is visible outside the namespace.
Client Dependencies
Text area. Lists the “depending” ends of the relationship, i.e. the end that makes use of the other end.
Button 1 double click navigates to the dependency and opens its property tab.
Button 2 click shows a pop-up menu with one entry
Add...
that
opens a dialog box where you can add and remove
depending modelelements.
Supplier Dependencies
Text area. Lists the “supplying” ends of the relationship, i.e. the end supplying what is needed by the other end.
Button 1 double click navigates to the dependency and opens its property tab.
Button 2 click shows a pop-up menu with one entry
Add...
that
opens a dialog box where you can add and remove
dependent modelelements.
Generalizations
Text area. Lists any class that generalizes this class.
Button 1 double click navigates to the generalization and opens its property tab.
Specializations
Text box. Lists any specialized class (i.e. for which this class is a generalization).
Button 1 double click navigates to the generalization and opens its property tab.
Attributes
Text area. Lists all the attributes (see Section 18.7, “ Attribute ”) defined for this class. Button 1 double click navigates to the selected attribute. Button 2 gives a pop up menu with two entries, which allow reordering the attributes.
Move Up
. Only available
where there are two or more attributes listed, and
the attribute selected is not at the top. It moves
the attribute up one position.
Move Down
. Only available
where there are two or more attributes listed, and
the attribute selected is not at the bottom. It
moves the attribute down one position.
Association Ends
Text box. Lists any association ends (see Section 18.12, “ Association ”) of associations connected to this class.
Button 1 double click navigates to the selected entry.
Operations
Text area. Lists all the operations (see Section 18.8, “ Operation ”) defined on this class. Button 1 click navigates to the selected operation. Button 2 gives a pop up menu with two entries, which allow reordering the operations.
Move Up
. Only available
where there are two or more operations listed, and
the operation selected is not at the top. It moves
the operation up one position.
Move Down
. Only available
where there are two or more operations listed, and
the operation selected is not at the bottom. It
moves the operation down one position.
Owned Elements
Text area. A listing of model elements contained within the classes' namespace. This is where any inner class (see Section 18.6.2, “ Class Property Toolbar ”) will appear
Button 1 double click on any of the model elements navigates to that model element.
![]() | Tip |
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Most namespace hierarchies should be managed through the package mechanism. Namespace hierarchies through classes are best restricted to inner classes. Conceivable datatypes, signals and interfaces could also appear here, but actors and use cases would seem of no value. |