Low-Level System Design

What Is Lld

Lld Vs Hld

Why Lld Matters

Lld Mindset Thinking In Components

Lld In Interviews Vs Real World

Prerequisites And Learning Path

From Procedural To Oo

Identifying Objects In Problem Statements

Entities Attributes Behaviors

Relationships Between Objects

State And Behavior Modeling

Real World To Code Translation

Why We Need Design Diagrams

Uml Overview

Class Diagrams

Relationships In Diagrams

Sequence Diagrams Behavior Over Time

Use Case Diagrams

Activity State Diagrams

When To Use Which Diagram

What Is Class What Is Object

Attributes And Methods

Constructors And Object Lifecycle

Access Modifiers Visibility

Static Vs Instance Members

Object Identity Equality Hashing

Designing Clean Classes

What Is Encapsulation

Data Hiding Principles

Getters And Setters When And Why

Immutable Objects

Defensive Copying

Encapsulation In Practice

What Is Inheritance

Is A Relationship

Method Overriding

Super Keyword Chain Calls

Inheritance Hierarchies Design

When Inheritance Goes Wrong

Abstract Classes

What Is Polymorphism

Compile Time Vs Runtime Polymorphism

Method Overloading

Method Overriding Revisited

Polymorphism Through Interfaces

Programming To Interfaces

Polymorphism Patterns Practice

What Is Abstraction

Abstract Classes Vs Interfaces

Designing For Abstraction

Abstraction Levels In System Design

The Cost Of Wrong Abstractions

Refactoring Toward Better Abstractions

Revisiting Inheritance Problems

What Is Composition

Has A Vs Is A Relationships

Favor Composition Over Inheritance

Delegation Pattern

When To Use Inheritance Vs Composition

Refactoring From Inheritance To Composition

What Is Srp

Defining Responsibility

Identifying Srp Violations

Refactoring For Srp

Srp At Different Levels

Common Srp Misconceptions

What Is Ocp

Open For Extension Closed For Modification

Achieving Ocp Through Abstraction

Strategy Pattern And Ocp

Ocp Violations And Fixes

Balancing Ocp With Pragmatism

What Is Lsp

Behavioral Subtyping

The Rectangle Square Problem

Preconditions And Postconditions

Invariants In Inheritance

Detecting And Fixing Lsp Violations

What Is Isp

Fat Interfaces Problem

Role Based Interface Design

Splitting Interfaces

Isp And Dependency Management

Isp In Practice

What Is Dip

High Level Vs Low Level Modules

Depending On Abstractions

Dependency Injection Fundamentals

Inversion Of Control Containers

Dip And Testability

Dry Dont Repeat Yourself

Kiss Keep It Simple Stupid

Yagni You Arent Gonna Need It

Law Of Demeter

Principle Of Least Astonishment

Tell Dont Ask

Separation Of Concerns

Cohesion And Coupling

What Are Design Patterns

History And Origins Gang Of Four

Pattern Categories

When To Use Patterns

Anti Patterns And Pattern Abuse

Pattern Selection Framework

Factory Method Pattern

Abstract Factory Pattern

Builder Pattern

Prototype Pattern

Singleton Pattern

Object Pool Pattern

Choosing The Right Creational Pattern

Adapter Pattern

Bridge Pattern

Composite Pattern

Decorator Pattern

Facade Pattern

Flyweight Pattern

Proxy Pattern

Choosing Structural Pattern

Strategy Pattern

Observer Pattern

Command Pattern

State Pattern

Template Method Pattern

Iterator Pattern

Chain Of Responsibility Pattern

Mediator Pattern

Memento Pattern

Visitor Pattern

Interpreter Pattern

Null Object Pattern

Choosing Behavioral Pattern

Dependency Injection Revisited

Constructor Injection

Setter Injection

Interface Injection

Service Locator Vs Dependency Injection

Ioc Container Deep Dive

Lifetime Management

Di Anti Patterns And Best Practices

Why Concurrency Matters

Threads And Processes

Thread Safety

Synchronization Primitives

Deadlocks And Prevention

Atomic Operations

Producer Consumer Pattern

Thread Pool Pattern

Read Write Lock Pattern

Future Promise Pattern

Double Checked Locking

Immutable Objects For Concurrency

Active Object Pattern

Introduction To Ddd

Entities

Value Objects

Aggregates

Repositories

Domain Events

Domain Services

Bounded Contexts

Why Architecture Matters

Traditional Layered Architecture

Hexagonal Architecture

Onion Architecture

Clean Architecture

Choosing An Architecture

Package Module Organization

What Is A Good Api

Method Signature Design

Error Handling In Apis

Api Versioning

Restful Api Design Principles

Dto Design

Api Documentation

Persistence Layer Responsibilities

Repository Pattern Deep Dive

Data Access Object Dao Pattern

Unit Of Work Pattern

Orm Considerations

Data Modeling For Lld

Database Transactions At Lld Level

Why Caching Matters

Cache Patterns

Cache Design Considerations

Cache Testing And Monitoring

Cache Invalidation Strategies

Caching In Object Design

Introduction To Event Driven Design

Domain Events

Event Handlers

Publish Subscribe Pattern

Event Sourcing Basics

Event Driven Integration

Testing Event Driven Designs

What Is Resource Management

Object Lifecycle Management

Disposable Pattern

Connection Pooling

Memory Management Considerations

Resource Acquisition Patterns

Testing Resource Management

Errors Vs Exceptions

Exception Hierarchy Design

Checked Vs Unchecked Exceptions

Error States And Result Types

Exception Handling Best Practices

Validation And Defensive Programming

Error Handling At Boundaries

Why Testing Matters For Lld

Unit Testing Fundamentals

Test Doubles Mocks Stubs Fakes

Mocking Dependencies

Test Driven Development Tdd

Testing Private Methods And Internals

Integration Testing At Lld Level

Code Coverage And Test Quality

Logging In Lld

Observability Design

Security Patterns

Secrets Management

Configuration Management

Feature Flags

Understanding Lld Problem Statements

Gathering Requirements

Identifying Core Entities

Defining Relationships

Applying Design Patterns

Validating The Design

Iterating And Refining

Parking Lot System

Library Management System

Elevator System

Chess Game

Ride Sharing Service

Hotel Booking System

What Interviewers Look For

Time Management In Lld Interviews

Clarifying Requirements

Communicating Your Design

Handling Constraints Trade Offs

Common Lld Interview Problems

From Design To Code

Code Organization Structure

Refactoring Toward Better Design

Continuous Learning