Rajat Gajbhiye

Complete Roadmap to become a Java Developer

Learn these things (preferably) in the given order:

➤ Core Java (Beginner to Advanced)
- Data Types, Variables, and Operators
- Control Statements (if, for, while, switch)
- Arrays and Strings
- Object-Oriented Programming (OOP): Inheritance, Polymorphism,
Encapsulation, Abstraction
- Exception Handling (try-catch-finally, custom exceptions)
- Collections Framework: List, Set, Map, Queue
- Generics and Annotations
- Java 8+ Features:
Lambda Expressions
Stream API
Functional Interfaces
Optional
Date and Time API

➤ Java Database Connectivity (JDBC)
- Setting up a connection with databases
- CRUD Operations
- Prepared Statements and Callable Statements
- Connection Pooling

➤ SQL (Database Skills)
- Basics: CREATE, SELECT, INSERT, UPDATE, DELETE
- Advanced Queries: Joins, Group By, Having, Subqueries
- Indexing and Optimization
- Transactions and ACID Properties
- Database Design and Normalization
- Stored Procedures and Triggers

➤ JSP and Servlets (Web Basics)
- Basics of HTTP and Web Servers
- Request/Response Lifecycle
- Session Management (Cookies, HttpSession)
- Form Handling
- MVC Architecture

➤ Spring Framework (Core Skills)
- Dependency Injection (DI) and Inversion of Control (IoC)
- Spring MVC (Model-View-Controller)
- AOP (Aspect-Oriented Programming)
- Spring Security: Authentication and Authorization

➤ Hibernate (ORM Skills)
- Introduction to ORM (Object Relational Mapping)
- Entity Mapping (One-to-One, One-to-Many, Many-to-Many)
- HQL (Hibernate Query Language)
- Caching and Performance Optimization

➤ Spring Boot (Advanced Skills)
- RESTful Web Services
- Microservices Architecture
- Spring Boot Starters
- Spring Data JPA
- Spring Cloud (for distributed systems)
- Actuator and Monitoring

➤ Build Tools and Version Control
- Maven and Gradle (Dependency Management)
- Git (Version Control)
- GitHub/GitLab/Bitbucket for Collaboration

➤ DevOps Basics
- Docker: Containerize Java Applications
- Kubernetes: Orchestrate Containers
- Jenkins: Continuous Integration/Deployment (CI/CD)

➤ Cloud Platforms
- AWS Fundamentals:
- Compute (EC2, Lambda)
- Storage (S3)
- Database (RDS, DynamoDB)
- Monitoring (CloudWatch)
- GCP/Azure (Optional but beneficial)

➤ Advanced Topics
- Design Patterns (Singleton, Factory, Observer, etc.)
- System Design Basics: Load Balancing, Caching, Database Sharding
- Low-Level Design (LLD): Object-Oriented Design, UML Diagrams
- High-Level Design (HLD): Scalability, Fault Tolerance, Distributed Systems
- Event-Driven Architecture: Kafka, RabbitMQ

➤ Data Structures and Algorithms (DSA)
- Arrays, Strings, Linked Lists, Stacks, Queues, Heaps
- Binary Trees, BST
- Graphs: BFS, DFS, Sorting and Searching Algorithms, DP

➤ Real-World Projects
- Top 16 projects: https://lnkd.in/dv9SMyiT

➤ 𝗝𝗼𝗶𝗻 𝗪𝗵𝗮𝘁𝘀𝗔𝗽𝗽 𝗖𝗵𝗮𝗻𝗻𝗲𝗹𝘀:
- https://lnkd.in/dQY6pBv4

Stay curious, keep sharing, keep learning !

Spring Boot Roadmap

PHASE 1 - Basics

• Creating a spring boot project using spring initializr
• Maven and gradle build tools
• Annotations
• Profiles and environment-specific configurations
• @getmapping, @postmapping, @putmapping, @deletemapping
• Handling path variables and request parameters
• Setting up database connection (h2, mysql, postgresql)
• Using jparepository and crudrepository
• Introduction to spring boot devtools
• Enabling hot reloading
• Spring batch, scheduling and cron expressions


PHASE 2-Intermediate

• Using @controlleradvice and @exceptionhandler
• Custom error responses and exception classes
• Global exception handling
• Basic authentication
• Configuring security for apis
• Implementing jwt (json web tokens) for stateless authentication
• Introduction to hateoas
• Versioning rest apis (uri, parameter, headers)
• Unit testing with junit and mockito
• Writing integration tests with spring boot test
• Testing restful services with mockmvc
• Exploring actuator endpoints
• Creating custom health indicators


PHASE 3 - Advanced

• Using @profile annotation
• Configuring environment-specific beans
• Switching profiles for different environments
• Setting up a spring cloud project
• Key components of spring cloud
• Setting up eureka server
• Registering microservices with eureka
• Service discovery in action
• Introduction to api gateway
• Setting up spring cloud gateway
• Configuring routes and filters
• Setting up spring cloud config server
• Managing configuration in a centralized repository
• Configuring spring boot applications to use config server


PHASE 4 - Microservices

• Introduction to inter-service communication
• Using resttemplate for synchronous communication
• Using feign client for simplified service calls
• Setting up resilience4j
• Configuring circuit breakers, retry in microservices
• Introduction to distributed tracing
• Setting up spring cloud sleuth
• Visualizing traces with zipkin
• Introduction to spring cloud bus
• Integrating with a message broker (rabbitmq, kafka)
• Broadcasting configuration changes across services
• Introduction to event-driven architecture
• Setting up spring cloud stream

This roadmap guide you through the essential skills and concepts.

Here are some repositories that have helped me dive deeper into Spring Boot:
- https://lnkd.in/dxFBncus
- https://lnkd.in/dB2i8Yxc
- https://lnkd.in/dnNCXVxy
- https://lnkd.in/diqd44Vr
- https://lnkd.in/dc2ADrZA

𝗝𝗼𝗶𝗻 𝗺𝘆 𝗧𝗲𝗹𝗲𝗴𝗿𝗮𝗺 𝗖𝗵𝗮𝗻𝗻𝗲𝗹 - https://lnkd.in/dxqEen4X

Stay curious, keep learning, keep sharing !

I screwed up 5 interviews because I didn’t solve my Low-Level Design (LLD) problems properly.

Here is a complete roadmap for learning Low-Level Design (LLD):

➤ 𝗙𝘂𝗻𝗱𝗮𝗺𝗲𝗻𝘁𝗮𝗹 𝗖𝗼𝗻𝗰𝗲𝗽𝘁𝘀:

1. Basics OOP Concepts:
- https://lnkd.in/dhX-yYnb
2. SOLID Principles:
- https://lnkd.in/drsM7izj
3. DRY, YAGNI and KISS Principle:
- https://lnkd.in/d7Dk9Mpb
- https://lnkd.in/dvdm2mgR

➤ 𝗗𝗲𝘀𝗶𝗴𝗻 𝗣𝗮𝘁𝘁𝗲𝗿𝗻𝘀

1. Creational Patterns
- Singleton, Factory Method, Abstract Factory, Builder, Prototype and Structural Patterns
- https://lnkd.in/dfr_3f-U
- https://lnkd.in/d2s88tuV

2. Adapter
- Facade, Decorator, Composite and Behavioral Patterns
- https://lnkd.in/dtiFe8AN

3. Strategy
- Iterator, Observer, Template Method, Command and State

➤ 𝗨𝗻𝗶𝗳𝗶𝗲𝗱 𝗠𝗼𝗱𝗲𝗹𝗶𝗻𝗴 𝗟𝗮𝗻𝗴𝘂𝗮𝗴𝗲 (𝗨𝗠𝗟)

1. Class Diagrams
- Class, Attributes, Methods, Interfaces, Abstract Class, Enumeration and Multiplicity
- https://lnkd.in/dxeh7vSz

2. Use Case, Sequence, Activity and State Machine Diagram
- https://lnkd.in/dgVYbmPA

➤ 𝗪𝗮𝘁𝗰𝗵 𝗥𝗲𝘀𝗼𝘂𝗿𝗰𝗲𝘀:

1. Shrayansh Jain: https://lnkd.in/dhW5VmFa
2. Gaurav Sen: https://lnkd.in/dgjFGmXc
3. The Code Mate: https://lnkd.in/d8_6yTSN
4. Soumyajit Bhattacharyay: https://lnkd.in/dFe4t5gZ

➤ 𝗧𝗼𝗽 𝗥𝗲𝗽𝗼𝘀𝗶𝘁𝗼𝗿𝗶𝗲𝘀 𝘁𝗼 𝗠𝗮𝘀𝘁𝗲𝗿 𝗟𝗟𝗗​:

- https://lnkd.in/dAb9m84N
- https://lnkd.in/dvzAdaGt
- https://lnkd.in/dXypcpR4
- https://lnkd.in/dBYMX7Ph

➤ 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗮𝗹 𝗘𝘅𝗮𝗺𝗽𝗹𝗲𝘀:

- Standard problem solutions: https://lnkd.in/dXypcpR4
- Practice questions: https://lnkd.in/dCMb2nFV

➤ 𝗦𝗲𝗹𝗳-𝗔𝘀𝘀𝗲𝘀𝘀𝗺𝗲𝗻𝘁:

- Question 1: https://lnkd.in/dQRCdKhs
- Question 2: https://lnkd.in/dHmEiE79

Just preparing for DSA is not going to get you selected. During technical interviews, you are expected to have some level of understanding of low-level designs.

𝗝𝗼𝗶𝗻 𝗺𝘆 𝗧𝗲𝗹𝗲𝗴𝗿𝗮𝗺 𝗖𝗵𝗮𝗻𝗻𝗲𝗹 - https://lnkd.in/dxqEen4X

Stay curious, keep learning, keep sharing !

#lowleveldesign #lld #designInterviews