Activity diagrams in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identify the correct purpose of an activity diagram

Which of the following best describes the main purpose of an activity diagram in system design?

A To illustrate the database schema and table relations

B To define the static structure of classes and their relationships

C To represent the physical deployment of software components

D To show the sequence of actions and decisions in a process flow

💡 Hint

Think about how activity diagrams help visualize workflows.

Activity diagrams focus on the flow of activities and decisions, showing how a process progresses step-by-step.

❓ Architecture

intermediate

Trace the flow in an activity diagram for user login

Given an activity diagram for a user login process, which step logically follows after 'Validate Credentials' if the credentials are correct?

A Grant access to the user dashboard

B Display error message

C Request password reset

D Log out the user

💡 Hint

Consider what happens when validation succeeds.

When credentials are valid, the system proceeds to grant access rather than showing errors or resetting passwords.

❓ scaling

advanced

Choose the best way to represent parallel activities in an activity diagram

In an activity diagram, how should you represent two activities that can happen at the same time?

A Use a merge node to combine activities

B Use a decision node to choose one activity

C Use a fork node to split the flow into parallel paths

D Use an initial node to start both activities sequentially

💡 Hint

Parallel means happening simultaneously, not choosing between options.

A fork node splits the flow into multiple parallel paths, allowing activities to run concurrently.

❓ tradeoff

advanced

Select the tradeoff when using activity diagrams for complex systems

What is a common tradeoff when using detailed activity diagrams for very complex systems?

A They simplify understanding by showing only high-level steps

B They can become cluttered and hard to read due to too many activities

C They eliminate the need for other UML diagrams

D They automatically generate code without errors

💡 Hint

Think about what happens when too many details are shown.

Detailed activity diagrams may become overwhelming and reduce clarity if too many activities and flows are included.

❓ estimation

expert

Estimate the number of swimlanes needed for a multi-role process

A process involves three roles: Customer, Sales Agent, and Manager. To clearly show responsibilities in an activity diagram, how many swimlanes should be used?

A Three swimlanes, one for each role

B Two swimlanes, grouping Customer and Sales Agent together

C Four swimlanes, adding one for system processes

D One swimlane for all roles combined

💡 Hint

Swimlanes separate activities by who performs them.

Each role should have its own swimlane to clearly show which activities belong to whom.