Classifier (UML)

A classifier is a category of Unified Modeling Language (UML) elements that have some common features, such as attributes or methods.

A classifier is an abstract metaclass classification concept that serves as a mechanism to show interfaces, classes, datatypes and components.

A classifier describes a set of instances that have common behavioral and structural features (operations and attributes, respectively).

A classifier is a namespace whose members can specify a generalization hierarchy by referencing its general classifiers.

A classifier is a type and can own generalizations, thereby making it possible to define generalization relationships to other classifiers.

A classifier is a redefinable element, as it is possible to redefine nested classifiers.

All objects that can have instances are classifiers.

Important Aspects

• A classifier defines a namespace.
• A classifier contains a set of features.
• A classifier is generalizable.

Types of UML Classifiers

• Class
• Component
• Datatype
• Interface
• Node
• Signal
• Subsystem
• Use Case

Predefined UML classifiers

• Actor
• Association
• Class
• Component
• Datatype
• Interface
• Node
• Signal
• Subsystem
• Use Case