The request
“Create an observer-pattern UML class diagram where Stock implements Subject and Investor and PriceDisplay implement Observer for stock price updates.”
Then tryAdd a NewsDisplay observer.Add a volume field to Stock.
What is in this drawing
Read the decisions behind it.
01
Modeled Subject and Observer as interfaces for extensibility.
02
Used aggregation to show the subject holds a collection of observers.
03
Added directed associations from observers back to the subject for state retrieval.
When designing systems requiring one-to-many dependencies and automatic notifications, such as event handling, monitoring, or publish-subscribe mechanisms.
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