On the state diagram and activity diagram of UML learning Note Dynamic diagram

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State diagram

Let me briefly understand what a state machine is.
① in daily life, state machines, we understand the machine to record the state of a given moment, changing its state or triggering an action according to different inputs for each given change.
② in UML, state machines consist of the various states of an object and the transitions that connect them, which are diagrams showing state and state transitions.
The ③ state diagram is essentially a state machine or a state machine special case. Consists of a line of arrows that represent the state of the node and that represents the state of the transition.

• Concept and classification of awareness States:

• The composition of the status diagram also includes:

? Activity Chart

An activity diagram is another dynamic view that describes the results of an object's state change caused by actions and actions, regardless of the event that caused the state to change.

• Graphic criteria for activity diagrams:
① Beginnings
"Action" describes the start state of the activity diagram
"Representation" Black Solid circle

② termination Point
"Action" describes the termination state of the activity diagram
"Presentation" Solid Circle Hollow Circle

③ Activities
"Action" can be done manually or automatically.
"Representation" Rounded rectangle

④ status
The state of the action activity
"Representation" Ellipse Rectangle

⑤ Conversion
"Action" describes an activity turning to another activity
"Representation" a solid segment with arrows pointing to the activity of the steering


• Composition of activity diagrams

? Action status differences in actions and activity diagrams in a state diagram

• Same point:
① are atomic, actions are either not executed, or they are completely executed and cannot be interrupted.
② execution time is very short

• Different points:
Action state and state diagram in different states, there can be no entry action and exit action, there can be no internal transfer

? Understanding the respective roles of activity diagrams and state diagrams

• Function of the state diagram:
① clearly describes the sequence of transitions between states, and the sequence of events can be clearly seen through the conversion sequence
② clear sequence of events helps programmers avoid the wrong sequence of events when developing programs
③ clearly describes the factors that must be triggered by a state transition, such as a delta event, guardianship conditions, and actions, to help programmers summarize the entry of illegal events.
④ by judging the branch that better describes the workflow because different conditions occur

• Function of the activity diagram:

? The difference between an activity diagram and a state diagram

• Purpose: The main purpose of the activity diagram is to describe the changes of the action and the object, while the state diagram is the behavior of the object, subsystem and system in the life cycle.
• state transitions in activity diagrams do not require any triggering events, and state diagrams require triggering events
• Action of the active chart can be placed in the lane, the state diagram can not

On the state diagram and activity diagram of UML learning Note Dynamic diagram