Inheritance and interface notation in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is inheritance in system design?

Inheritance allows a new component or class to reuse properties and behaviors of an existing one, promoting code reuse and easier maintenance.

beginner

What does an interface represent in system design?

An interface defines a contract of methods or behaviors that a component must implement, without specifying how these methods work internally.

intermediate

How is inheritance typically shown in diagrams?

Inheritance is shown with a solid line and a hollow arrow pointing from the child (subclass) to the parent (superclass).

intermediate

How is interface implementation shown in diagrams?

Interface implementation is shown with a dashed line and a hollow arrow pointing from the implementing class to the interface.

advanced

Why use interfaces instead of inheritance?

Interfaces allow different components to share common behaviors without forcing a class hierarchy, enabling more flexible and decoupled designs.

Which notation represents inheritance in UML diagrams?

A Solid line with hollow arrow

B Dashed line with hollow arrow

C Solid line with filled arrow

D Dashed line with filled arrow

Inheritance is shown with a solid line and a hollow arrow pointing to the parent class.

What does an interface specify?

A A contract of methods to implement

B How methods work internally

C Data storage details

D Inheritance hierarchy

Interfaces specify a contract of methods that must be implemented, without defining internal workings.

Which line style shows interface implementation?

A Solid line

B Dotted line

C Double line

D Dashed line

Interface implementation is shown with a dashed line and a hollow arrow.

Inheritance promotes which of the following?

A Loose coupling

B Code reuse

C Interface segregation

D Data hiding

Inheritance allows reuse of code by sharing properties and behaviors from parent to child.

Why might you prefer interfaces over inheritance?

A To force a strict class hierarchy

B To avoid defining any methods

C To allow flexible behavior sharing without hierarchy

D To increase coupling

Interfaces allow different classes to share behaviors without being forced into a class hierarchy.

Explain how inheritance and interface notation differ in system design diagrams.

Think about the line style and arrow type used in UML.

Describe why interfaces are important in designing flexible systems compared to inheritance.

Consider how interfaces help avoid rigid class structures.