Use case diagrams in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a use case diagram?

A use case diagram is a simple visual tool that shows how users (actors) interact with a system to achieve goals (use cases). It helps understand system functions from the user's perspective.

beginner

Who are actors in a use case diagram?

Actors represent users or other systems that interact with the system. They can be people, external systems, or devices that perform actions with the system.

beginner

What is the purpose of use cases in a use case diagram?

Use cases describe specific actions or services the system provides to actors. They represent goals or tasks that actors want to accomplish using the system.

beginner

What does an association line represent in a use case diagram?

An association line connects an actor to a use case, showing that the actor participates in or initiates that use case.

intermediate

How do use case diagrams help in system design?

They help clarify system requirements by showing who uses the system and what they want to do. This makes it easier to plan features and communicate with stakeholders.

What does an actor represent in a use case diagram?

A A database inside the system

B A user or external system interacting with the system

C A programming function

D A hardware component

Actors are users or external systems that interact with the system.

What is the main purpose of a use case in a use case diagram?

A To show the system's internal code structure

B To list all system errors

C To represent the physical hardware

D To describe a goal or task an actor wants to achieve

Use cases describe goals or tasks actors want to accomplish using the system.

Which symbol typically represents an actor in a use case diagram?

A A stick figure

B A rectangle

C A circle

D A diamond

Actors are usually shown as stick figures to represent users or external entities.

What does a line connecting an actor to a use case indicate?

A The use case is a subtask of the actor

B The actor owns the use case

C The actor interacts with the use case

D The actor is a system component

The line shows the actor participates in or initiates the use case.

Why are use case diagrams useful in early system design?

A They help understand user needs and system functions

B They replace all other diagrams

C They show detailed code logic

D They show database schemas

Use case diagrams help clarify user needs and system functions early on.

Explain what a use case diagram is and describe its main components.

Think about who uses the system and what they want to do.

Describe how use case diagrams help in understanding system requirements.

Consider how diagrams help talk with users and developers.