About UML class diagrams

The concept topics about Unified Modeling Language (UML) visualization class diagrams help you better understand and use the features to examine and design structures and relationships of Java 2 Platform, Enterprise Edition (J2EE), Java 2 Platform, Standard Edition (J2SE), and database applications.

Class diagrams
In UML visualization, a Unified Modeling Language (UML) class diagram provides a graphical representation of the structures and relationships of elements in an application.

Class shapes
In Unified Modeling Language (UML) visualization class diagrams, a class shape is a graphical element that represent an application element. An application element can be represented by multiple instances of a class shape in one or more diagrams.

Classifiers
In UML visualization, a classifier is the superclass of classes, interfaces, and data types that have similar syntax and, therefore, are all notated by using a rectangle with keywords.

Classes
In UML visualization, classes are Unified Modeling Language (UML) diagram elements that represent abstractions of an object or set of objects that share a common structure and behavior.

Relationships
In Unified Modeling Language (UML) visualization class diagrams, a relationship is the connection between Java classes or interfaces or between Enterprise JavaBeans (EJB) enterprise beans.

Attributes
In Unified Modeling Language (UML) visualization class diagrams, an attribute represents a data definition for an instance of a classifier. An attribute describes a range of values for that data definition.

Operations
In Unified Modeling Language (UML) visualization class diagrams, an operation requests a service that a classifier or an instance of a class is called to perform. Operations are contained by classes and interfaces. A classifier can have any number of operations or none at all.

Adornments for unresolved references
In Unified Modeling Language (UML) visualization class diagrams, Java classes and interfaces or Enterprise JavaBeans (EJB) enterprise beans belonging to different applications or projects that are not currently loaded in the workspace can result in an unresolved reference.

Multiplicity
In Unified Modeling Language (UML) visualization class diagrams, multiplicity specifies the number of allowable elements that a set of associated Enterprise JavaBeans (EJB) enterprise beans might assume.

Visibility
In Unified Modeling Language (UML) visualization class diagrams, visibility defines whether attributes and operations of specific classes can be seen and used by other classes.