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Association here means number of instances.?

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#1

The class diagram has the following association relationships:

  • The ParkingSpot has a one-way association with Vehicle.
  • The Vehicle has a one-way association with ParkingTicket.
  • The Payment has a two-way association with ParkingTicket.

Course: Grokking the Low Level Design Interview Using OOD Principles - Learn Interactively
Lesson: Class Diagram for the Parking Lot - Grokking the Low Level Design Interview Using OOD Principles

#2

Hi @Thirumavalavan !!
In this lesson, the term “association” refers to the relationships between classes and does not specifically imply a specific number of instances. Instead, it describes how classes are related or connected to each other within the system’s design.

Let’s break down the associations mentioned in the class diagram:

  1. “The ParkingSpot has a one-way association with Vehicle”:

    • This means that each instance of a ParkingSpot is associated with a Vehicle. However, it doesn’t specify the exact number of instances of Vehicle associated with a ParkingSpot. It simply indicates that a ParkingSpot is related to a Vehicle.

  2. “The Vehicle has a one-way association with ParkingTicket”:

    • Similarly, this association suggests that each instance of a Vehicle is associated with a ParkingTicket, but it doesn’t specify how many ParkingTickets are associated with a single Vehicle.

  3. “The Payment has a two-way association with ParkingTicket”:

    • In this case, it implies a bidirectional association. Each instance of Payment is associated with one or more instances of ParkingTicket, and each ParkingTicket is associated with a Payment. Again, it doesn’t specify the exact number of instances involved in the association.

Associations in class diagrams define the relationships and connections between classes, but they don’t necessarily dictate the exact quantity or cardinality of instances involved. The cardinality (e.g., one-to-one, one-to-many, many-to-many) can be further specified in the class diagram if needed, but the lesson content primarily focuses on establishing these relationships conceptually.
I hope it helps. Happy Learning :blush: