OBJECT DESIGN · LLD · EASY CODEX

Object Design · LLD Interview Questions — Easy

Q: What is Low-Level Design (LLD) and how does it fit into the software development life cycle?

- LLD (Object-Oriented Design): The process of translating business requirements and high-level architecture (HLD) into a detailed, executable blueprint containing classes, interfaces, relationships,

Q: What is the main objective of LLD?

- Objectives: - Guarantee maintainability, readability, and testability of the code. - Implement structural SOLID principles and standard design patterns. - Establish clear boundaries, class interface

Q: What are the primary inputs and outputs of the LLD phase?

- Inputs: HLD documentation, System Use Cases, Functional Requirements, Database Schemas, API contracts. - Outputs: Class diagrams, Sequence diagrams, State-machine diagrams, detailed interface specif

Q: What is Object-Oriented Analysis and Design (OOAD)?

- Analysis (OOA): Identifying the core business domain entities, their attributes, and operations from the requirements (e.g., identifying "User", "Order", "Cart" in e-commerce). - Design (OOD): Struc

Q: Explain the Single Responsibility Principle (SRP) with an LLD example.

- SRP: A class should have exactly one reason to change. - LLD Example: Instead of an Invoice class that handles both calculations and PDF generation, split it into two: - Invoice: Manages invoice dat

Core concepts, definitions, basic syntax, and first principles expected in round 1 screening.

50 Theory Questions5 Free Model Answers

THEORY QUESTIONS & SOLUTIONSShowing 5 of 50 questions

Q1What is Low-Level Design (LLD) and how does it fit into the software development life cycle?

LLD (Object-Oriented Design): The process of translating business requirements and high-level architecture (HLD) into a detailed, executable blueprint containing classes, interfaces, relationships, and design patterns.
SDLC Fit: It bridges the gap between High-Level Design (HLD) (services, databases, system architecture) and actual coding/implementation.

Q2What is the main objective of LLD?

Objectives:
- Guarantee maintainability, readability, and testability of the code.
- Implement structural SOLID principles and standard design patterns.
- Establish clear boundaries, class interfaces, and modular lifecycles.
- Reduce the risk of bugs by defining rigorous interaction protocols (UML) before writing code.

Q3What are the primary inputs and outputs of the LLD phase?

Inputs: HLD documentation, System Use Cases, Functional Requirements, Database Schemas, API contracts.
Outputs: Class diagrams, Sequence diagrams, State-machine diagrams, detailed interface specifications, and database schema mappings (ERD).

Q4What is Object-Oriented Analysis and Design (OOAD)?

Analysis (OOA): Identifying the core business domain entities, their attributes, and operations from the requirements (e.g., identifying "User", "Order", "Cart" in e-commerce).
Design (OOD): Structuring these entities into concrete software components (classes, interfaces), assigning behaviors, and arranging their interactions.

Q5Explain the Single Responsibility Principle (SRP) with an LLD example.

SRP: A class should have exactly one reason to change.
LLD Example: Instead of an Invoice class that handles both calculations and PDF generation, split it into two:
- Invoice: Manages invoice data and mathematical calculations.
- InvoicePDFGenerator: Exclusively handles formatting and rendering of the PDF file.

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