Class diagrams in Software Engineering - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Class Diagram Components

Which of the following best describes the role of associations in a class diagram?

A They represent the connections and interactions between classes.

B They define the internal methods of a class.

C They show the inheritance relationship between classes.

D They specify the data types of class attributes.

💡 Hint

Think about how classes relate to each other in a system.

Associations in class diagrams represent how classes are connected or interact with each other, such as one class using or referencing another.

📋 Factual

intermediate

Multiplicity in Class Diagrams

In a class diagram, what does a multiplicity of 1..* on an association mean?

A At least one instance, possibly many, are required.

B Zero or more instances are allowed.

C Exactly one instance is required.

D No instances are allowed.

💡 Hint

Look at the range indicated by the numbers.

The notation 1..* means there must be at least one instance, but there can be many.

🔍 Analysis

advanced

Interpreting Inheritance in Class Diagrams

Given a class diagram where class Vehicle is connected to class Car with a solid line and a hollow triangle pointing to Vehicle, what does this indicate?

A <code>Car</code> and <code>Vehicle</code> are unrelated classes.

B <code>Vehicle</code> is a subclass that inherits from <code>Car</code>.

C <code>Car</code> is a subclass that inherits from <code>Vehicle</code>.

D <code>Car</code> uses <code>Vehicle</code> as an attribute.

💡 Hint

Recall the meaning of the hollow triangle arrow in UML.

The hollow triangle arrow points to the parent class, indicating inheritance. Here, Car inherits from Vehicle.

❓ Comparison

advanced

Difference Between Aggregation and Composition

Which statement correctly distinguishes aggregation from composition in class diagrams?

A Aggregation implies ownership and strong lifecycle dependency; composition does not.

B Aggregation and composition are the same and can be used interchangeably.

C Both aggregation and composition imply no ownership between classes.

D Composition implies ownership and strong lifecycle dependency; aggregation does not.

💡 Hint

Think about how the lifetime of parts relates to the whole.

Composition means the part cannot exist without the whole (strong lifecycle dependency), while aggregation means the part can exist independently.

❓ Reasoning

expert

Determining Class Responsibilities from a Diagram

In a class diagram, the class Order has attributes orderID and date, and methods calculateTotal() and addItem(). Which of the following best describes the responsibility of the Order class?

A It only stores order details but does not manage items.

B It stores order details and manages the list of items in the order.

C It only calculates totals but does not store any data.

D It manages customer information unrelated to orders.

💡 Hint

Look at both attributes and methods to understand the class role.

The attributes store order details, and methods like addItem() and calculateTotal() show it manages items and calculations related to the order.