UML learning notes (1) -- object class diagram

Object Class diagram: Class, attribute, connection (Association, generalization, aggregation, combination, dependency), interface, and constraint.

(Note: static attributes are underlined)

Interface ). The operation set used to describe a service of a class or component.

Data Type (datatype ). A type whose values are unchangeable, including simple built-in types (such as numbers and strings) and enumeration types (such as Boolean ).

Association ). Description of a group of links. Each link is associated with two or more objects.

Signal (signal ). Description of asynchronous messages transmitted between instances.

Component ). The modular part of the system, which hides its implementation behind a set of external interfaces.

Node ). The physical element that exists during running. It indicates computing resources. Generally, it has at least a certain amount of memory and is often capable of processing.

Use Case ). A description of a set of action sequences (including variants) that the system executes to generate observed results for specific participants.

Subsystem (subsystem ). Describes the components of a system.

In UML, abstract classes or abstract methods (such as icon and icon: Display () are represented in italics, and leaf labels are used to represent leaf classes or leaf methods (such as okbutton and icon :: GETID (), the leaf class does not have any subclass, and the leaf method is not polymorphism.

In practice, the number of instances may be limited, and there may be no instances (only static methods), one instance (single class), or multiple instances. The number of instances that a class may have is called a multiple. In UML, a multiple expression is marked in the upper right corner to specify the multiple classes.
Multiple features can also be applied to attributes. leleport can have at least two instances.

in UML, the complete Syntax of attributes is:
[visibility] attribute name [': 'Type] ['['multiplease']'] ['= 'initial value] [feature string {', 'feature string}]
in UML, the complete syntax of the operation is as follows:
[visibility] operation name ['('parameters')'] [': 'Return type] [feature string {', 'feature string}]