A comprehensive, modern guide to becoming a confident Java developer — built from 10+ years of training thousands of students across India and beyond.
TL;DR: The 7 Phases at a Glance
| Phase | Focus | Key Outcome |
|---|---|---|
| 0 | Tools & Environment | Java 25, IntelliJ, Git ready |
| 1 | Computational Thinking | Logic before language |
| 2 | Methods & Functions | Decompose problems |
| 3A | Core OOP | Classes, inheritance, interfaces |
| 3B | Advanced OOP | Exceptions, threads, generics |
| 4 | Modern Java | Collections, streams, records, virtual threads |
| 5 | Data & Persistence | SQL, JDBC, JPA |
| 6 | Spring Boot 4 | REST APIs, AI integration |
| 7 | Professional Practices | Testing, Docker, CI/CD |
Time investment: 6-12 months of consistent practice. No shortcuts.
This Post is For You If...
You want to learn Java — properly. Not the "watch a 4-hour crash course and call yourself a developer" kind of learning. The real kind. The kind where you actually understand what you're writing, why you're writing it, and how to build software that solves real problems.
It doesn't matter who you are:
- A first-year engineering student staring at your first programming course
- A final-year student panicking about placements
- A working professional from a non-tech background looking to switch careers
- A self-taught learner who's been "learning Java" for months but still feels lost
- Someone who already "knows" Java from college but can't build anything real with it
Java doesn't care about your background. Neither does this roadmap.
What matters is your willingness to put in the work. There are no shortcuts.
The Project: JanSahayak (जनसहायक — Citizen's Assistant)
Before we dive into the phases, let me tell you what you'll build. Because learning without purpose is just academic exercise.
I refuse to make you build a todo app. It's the most overused, uninspiring project in programming education. Nobody wants to look at it. Nobody is impressed by it.
Instead, you'll build JanSahayak — an AI-powered platform that helps citizens navigate government schemes, understand required documents, and access local services. This project evolves through all phases of the roadmap:
| Phase | Implementation |
|---|---|
| Phase 1 | CLI tool: "What documents do I need for X?" |
| Phase 2 | Refactored with methods, file I/O for data storage |
| Phase 3 | OOP design: Citizen, Document, Scheme, Service classes |
| Phase 4 | Modern Java: Records for DTOs, Streams for processing |
| Phase 5 | Database integration with PostgreSQL |
| Phase 6 | REST API with Spring Boot 4, AI-powered with Spring AI |
| Phase 7 | Dockerized, tested, deployed with CI/CD |
Choose Your Own Adventure
Don't like JanSahayak? Choose a different domain with the same architecture:
- KisanMitra (किसानमित्र) — Agricultural advisory platform
- SwasthyaSathi (स्वास्थ्यसाथी) — Health information assistant
- VidyaSahay (विद्यासहाय) — Educational resource navigator
- RojgarDoot (रोज़गारदूत) — Job/skill matching platform
Or pick a problem from the Smart India Hackathon — real problems that real organizations need solved. Check out the problem statements for inspiration.
The architecture blueprint remains the same. The domain is your choice.
The Question I've Been Asked 10,000 Times
"Sir, how do I get started with Java?"
I've been teaching and training developers since 2014 (officially since 2018), and this question has never stopped coming. Not once. Every batch, every bootcamp, every institution — the same question, the same anxiety in the eyes.
And here's the thing: it's a good question. Perhaps the most important question a beginner can ask. Because how you start determines everything that follows.
Back in 2021, I wrote a roadmap that went viral in the Java community. Every major Java Twitter account shared it. Students from across the world reached out saying it helped them find direction.
But 2021 was a different world. The job market was different. The technology was different. Java itself is different now.
So here we are — a refreshed, battle-tested roadmap for 2026 and beyond.
2021 vs 2026: How the Industry Has Changed
Five years might not seem like much, but in technology, it's an eternity. Here's what's changed since my original roadmap:
What a Java Developer Needed in 2021
| Area | 2021 Requirements |
|---|---|
| Java Version | Java 11 or 16, with Java 8 still common |
| Learning Approach | Start with public static void main, explain ceremony later |
| Spring Version | Spring Boot 2.x |
| AI Integration | Not expected |
| Concurrency | Traditional threads, ExecutorService |
| Testing | Nice to have, often learned "later" |
| DevOps | Optional for beginners |
| Problem Solving | Focus on competitive programming sites |
What a Java Developer Needs in 2026
| Area | 2026 Requirements |
|---|---|
| Java Version | Java 25 LTS (released September 16, 2025) with modern features as defaults |
| Learning Approach | Computation-first with simplified syntax |
| Spring Version | Spring Boot 4 (released November 20, 2025) with Spring Framework 7 |
| AI Integration | Spring AI is table stakes |
| Concurrency | Virtual Threads (stable), Structured Concurrency (preview) |
| Testing | Non-negotiable from day one; JUnit 6 is the new default |
| DevOps | Docker, CI/CD expected for entry-level |
| Problem Solving | Real-world projects with hackathon-style challenges |
The Skill Gap Reality
In 2021, knowing Core Java well could get you interviews. In 2026, that's just the starting line.
New mandatory skills:
- AI Integration: Companies expect you to use AI tools effectively AND build AI-powered features
- Modern Java Features: Records, pattern matching, sealed classes aren't "advanced" — they're baseline
- Virtual Threads: The old thread-pool-for-everything approach is outdated
- API Design: REST isn't enough; you need API versioning, GraphQL awareness
- Observability: OpenTelemetry, metrics, and tracing from day one
Skills that evolved:
- Spring: From Boot 2.x to Boot 4.0 — completely different paradigm with modular codebase, null safety, and HTTP Service Clients
- Testing: From "write tests when you have time" to TDD being expected; JUnit 6 is now the default in Spring Boot 4
- Version Control: From basic Git to full PR workflows with conventional commits
The uncomfortable truth: The 2021 roadmap's four stages (Syntax → OOP → Collections → Problem Solving) produced developers who could pass coding tests. The 2026 reality demands developers who can build, deploy, and maintain production software.
Why Continuous Learning is Non-Negotiable
Look at this progression:
2021: Java 16, Spring Boot 2.4, traditional threads
2022: Java 17 LTS, Spring Boot 2.7, virtual threads preview
2023: Java 21 LTS, Spring Boot 3.0, pattern matching stable
2024: Java 23, Spring Boot 3.3, structured concurrency preview
2025: Java 25 LTS, Spring Boot 4.0, AI integration standard
2026: You are here. What's next?
The developers who thrived through these changes weren't necessarily the smartest — they were the ones who never stopped learning. They stayed curious. They didn't just learn Java once; they evolved with it.
This industry will leave you behind if you stand still. That's not meant to scare you — it's meant to prepare you. The good news? Java has been evolving beautifully, and each evolution has made developer lives easier, not harder.
Before We Begin: Some Hard Truths
Truth #1: Learning a Programming Language is Like Learning a Spoken Language
Your brain needs to rewire itself. You need to think differently. You'll be frustrated, confused, and occasionally wonder if you're smart enough for this.
You are. Everyone goes through this. The difference between those who succeed and those who give up isn't intelligence — it's persistence. The willingness to sit with confusion until clarity arrives. The discipline to practice even when it's boring.
Truth #2: There is No "Advanced" Java
Let me say something that might surprise you: the distinction between "Core Java" and "Advanced Java" is largely a market gimmick.
Yes, it made sense in the 1990s when object-oriented programming was a paradigm shift. But today? Every modern language has adopted these concepts. The "advanced" features (lambdas, streams, records, pattern matching) aren't advanced — they're just Java. They're better defaults that the language now promotes.
When someone asks me if they should "first complete Core Java before moving to Advanced Java," I tell them they're asking the wrong question. You should learn Java — all of it — progressively, as you need it. The language is one continuous journey, not two separate destinations.
Truth #3: What Programming Languages Actually Do
Here's something many beginners miss: every programming language does the same fundamental thing — it tells a computer what to do.
In the end, everything becomes 1s and 0s for your CPU. It doesn't matter what language you use to write your next application. Languages exist for the efficiency and benefit of developers, not computers.
Java gives you a particular set of tools and patterns that work exceptionally well for building large-scale, maintainable, enterprise-grade software. That's why it's been among the world's most popular languages for three decades.
Truth #4: AI Will Not Replace You (But It Will Change How You Work)
I see the anxiety in my students' eyes when they ask: "Sir, will AI replace programmers?"
No. And here's why.
AI is a tool, governed by rules, just like any other tool. A hammer doesn't replace a carpenter. A calculator doesn't replace a mathematician. AI doesn't replace programmers — it amplifies them.
But here's the catch: a tool is only as good as the person wielding it.
If you don't understand what code does, you can't verify if AI-generated code is correct. You can't debug it. You can't improve it. You can't explain it in an interview. You become a "vibe coder" — someone who prompts AI until something works, without understanding why it works.
The developers who will thrive are those who use AI to accelerate their work while maintaining deep understanding. Who use AI to learn faster, not to avoid learning altogether.
That's what this roadmap will teach you to do.
The 2026 Transformation: Java's New On-Ramp
Something remarkable happened with Java 25 LTS (released September 16, 2025). The language designers finally addressed a problem that educators have complained about for 25 years: the ceremony required to write your first program.
Brian Goetz (Java's Language Architect at Oracle) and the team designed what they call a "smooth on-ramp" to Java programming.
The classic "Hello World" in Java used to look like this:
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World");
}
}
Five lines packed with concepts a beginner can't possibly understand on day one:
-
public(twice!) — access modifiers -
class— object-oriented programming -
static— a concept that creates bad habits that must be unlearned -
void— return types -
String[] args— arrays and command-line arguments -
System.out.println— three different concepts chained together
Now, in Java 25, your first program looks like this:
void main() {
println("Hello World");
}
That's it. No ceremony. No magic incantations. Just logic.
And here's the beautiful part: when you're ready to learn about classes, access modifiers, and the static keyword, you simply add them to what you already know. Nothing needs to be unlearned.
The Roadmap: A Computation-First Approach
Based on years of teaching experience and the latest pedagogical research, I recommend what I call a Computation-First approach. Here's the philosophy:
| Phase | Focus | Why |
|---|---|---|
| Phase 0 | Environment & Tools | You can't learn to drive without a car |
| Phase 1 | Computational Thinking | Focus on logic, not language ceremony |
| Phase 2 | Functions & Methods | Decompose problems into reusable blocks |
| Phase 3A | Core Object-Oriented Thinking | Model the real world with classes and objects |
| Phase 3B | Advanced OOP Patterns | Exceptions, threads, generics |
| Phase 4 | Modern Java | Collections, streams, records, virtual threads |
| Phase 5 | Data & Persistence | Databases, JDBC, JPA |
| Phase 6 | Spring Boot 4 & APIs | Build real backend applications with AI integration |
| Phase 7 | Professional Practices | Testing, Docker, CI/CD, Git workflows |
Let me walk you through each phase.
Phase 0: Your Toolkit
Before you write a single line of code, you need your tools ready.
Required:
- Java 25 LTS — Download from the official OpenJDK site or use SDKMAN
- IntelliJ IDEA — The 2025.3 release unified Community and Ultimate editions into a single product; core features remain free for both commercial and non-commercial use
- Git — Version control is non-negotiable in 2026
- GitHub Account — Your code needs a home
- A Reference Book — I recommend "Java: A Beginner's Guide" by Herbert Schildt (9th Edition)
Why IntelliJ?
I know VS Code is popular. If you're on a limited machine and VS Code is your only option, that's fine — I'll sprinkle in guidance for you throughout the reference document.
But IntelliJ is purpose-built for Java. Its code completion, refactoring tools, and debugger will teach you as you code. With the unified 2025.3 release, you get a single installer with core Java development features free out of the box, plus a 30-day trial of advanced features.
Why Git from Day 1?
Because every piece of code you write should be version-controlled. This isn't optional. This isn't "something you'll learn later." From your very first program, you'll be committing, pushing, and building a history of your learning journey.
Phase 1: Computational Foundations
Goal: Think like a programmer. Express logic in code.
Using Java 25's simplified syntax, you'll learn to solve problems before worrying about language ceremony. This phase is about training your brain to break down problems into steps a computer can execute.
1.1 Syntax and Semantics
-
Data Types (The 8 Java Primitive Types:
byte,short,int,long,float,double,char,boolean) -
Variables (declaration, initialization, the
varkeyword) - Type Conversion & Casting (widening, narrowing, explicit casting)
- Automatic Type Promotion in Expressions
-
Arrays (single-dimensional, multi-dimensional,
lengthproperty) - Operators in Java: Arithmetic, Bitwise, Relational, Boolean, Assignment, Ternary, and Operator Precedence
-
Control Statements:
if,if-else,if-else-ifladder,switchstatement (traditional and modern switch expressions) -
Iteration Statements:
while,do-while,for, enhancedfor-each, nested loops,break,continue, and labeled statements - Using Command-Line Arguments
- The
Stringclass (creation, immutability, common methods) - Varargs (Variable Length Arguments)
-
Scannerclass for input -
BufferedReaderclass for efficient input
The key insight: At this phase, you're not learning "Java." You're learning to think computationally. The syntax is just how you express those thoughts.
Practice: CodingBat — Start with Warmup-1, String-1, Array-1. Don't move forward until you can solve these without looking up syntax.
Phase Complete Checkpoint
Before moving to Phase 2, you should be able to:
- Write a program that reads input and produces output based on conditions
- Use loops to process collections of data
- Explain why
int x = 10/3gives you3, not3.333 - Debug a simple program by reading error messages
Phase 2: Functions & Methods
Goal: Break problems into smaller, reusable pieces.
Methods are the building blocks of all software. Before you learn about objects, you need to master the art of decomposing problems into functions that do one thing well.
2.1 Methods
- Declaring and Using Methods (method signature, method body)
- Method Return Types (
voidand value-returning methods) - Method Parameters and Arguments
- Pass by Value semantics in Java
- Method Overloading (same name, different parameters)
- Recursion (base case, recursive case, call stack, tail recursion, head recursion)
- Variable Scope (local variables, block scope, shadowing)
- The Call Stack and Stack Frames
Why this before OOP?
Because understanding methods is foundational. A class is just a container for related methods and data. If you don't understand methods, classes will feel like magic.
Practice: Complete CodingBat Logic-1, Logic-2, String-2. Then move to Exercism Java Track for more substantial exercises.
Phase Complete Checkpoint
Before moving to Phase 3A, you should be able to:
- Extract repeated code into a method
- Write a recursive function to solve a simple problem (like factorial or Fibonacci)
- Explain what the call stack is and why it matters
- Overload a method with different parameter types
Phase 3A: Core Object-Oriented Programming
Goal: Learn to model the real world using classes and objects.
You've been writing programs as sequences of instructions. Now comes the paradigm shift: instead of doing things, you'll define things that do. A Citizen isn't a list of variables—it's an entity with identity, state, and behavior.
This phase builds the mental model that powers enterprise Java. Take your time here.
3.1 Classes and Objects
Every Java program you've written has secretly been using classes. Now you'll create your own.
- Types of Program Units in Java (Class, Abstract Class, Interface, Enum, Record)
- Declaring Classes
-
Creating Objects (the
newkeyword, object references) - Reference Types vs Primitive Types
- Instance Variables (Fields)
- Methods (instance methods, method signatures)
- Constructors (default constructor, parameterized constructors)
- The
thiskeyword - Overloading Constructors
- Using Objects as Method Parameters and Return Types
-
The
statickeyword (static fields, static methods, static blocks) -
The
finalkeyword (final classes, final methods, final variables/constants) - Nested Classes and Inner Classes
3.2 Inheritance
Inheritance lets you build on existing code without rewriting it. It's one of the most powerful tools for code reuse—but also one of the most misused.
-
Inheritance in Java (
extendskeyword) - Superclass and Subclass relationships
- The
superkeyword - Types of Inheritance Hierarchies (single, multilevel)
-
Method Overriding and the
@Overrideannotation - Polymorphism (runtime polymorphism, dynamic method dispatch)
3.3 Abstract Classes and Interfaces
These define contracts that classes must fulfill. They're the foundation of flexible, maintainable architecture.
- Abstract Classes (abstract methods, concrete methods)
- Interfaces (defining, implementing, multiple inheritance of type)
- Default Methods in Interfaces
- Static Methods in Interfaces
- Private Methods in Interfaces (Java 9+)
- Functional Interfaces (single abstract method)
3.4 Packages and Access Control
Encapsulation is about hiding complexity. Packages and access modifiers are your tools for building clean, maintainable systems.
-
Packages (creating, naming conventions,
CLASSPATH) - Importing Packages
-
Access Modifiers (
public,protected, default/package-private,private) - Encapsulation and Information Hiding
Practice: Complete Exercism's "Classes" and "Inheritance" exercises in the Java track.
Phase Complete Checkpoint
Before moving to Phase 3B, you should be able to:
- Create a class with private fields, a constructor, and getter methods
- Explain why we hide data behind methods (not just "because OOP says so")
- Write a simple inheritance hierarchy without looking up syntax
- Implement an interface and explain when to use interface vs abstract class
Phase 3B: Advanced OOP Patterns
Goal: Master the constructs that enable large-scale, maintainable code.
Core OOP taught you to think in objects. This phase teaches you to think in systems of objects—how they communicate, what they guarantee to each other, and how they fail gracefully.
3.5 Exception Handling
When something goes wrong (and it will), you need a plan. Exception handling is how Java programs deal with errors gracefully.
-
Exception Types (checked vs unchecked,
ErrorvsException) - The Exception Hierarchy
try-catchblocksfinallyblock- try-with-resources (automatic resource management)
- Multiple catch blocks and multi-catch
-
throwandthrowskeywords - Creating Custom Exceptions
3.6 Multithreaded Programming Basics
Concurrency is how programs do multiple things at once. Understanding the basics prepares you for modern concurrency in Phase 4.
- The Java Thread Model
- The Main Thread
-
Creating Threads (
Threadclass,Runnableinterface) - Thread Lifecycle and States
-
sleep(),join(), thread priorities - Synchronization basics
3.7 Enumerations and Annotations
Enums give you type-safe constants. Annotations let you add metadata to your code that tools can process.
- Enum Types (declaration, methods, constructors)
-
Type Wrappers (
Integer,Double,Boolean, etc.) - Autoboxing and Unboxing
-
Annotations (
@Override,@Deprecated,@SuppressWarnings, custom annotations)
3.8 Generics
Generics let you write code that works with any type while maintaining type safety. They're essential for understanding collections and modern Java APIs.
- Introduction to Generics
- Generic Classes
- Generic Methods
-
Bounded Type Parameters (
extends,super) -
Wildcards (
?,? extends T,? super T) - Type Erasure
- Generic Constructors
Practice: Complete Exercism's "Generics" and "Exception Handling" exercises.
Phase Complete Checkpoint
Before moving to Phase 4, you should be able to:
- Handle an exception you intentionally throw
- Create a generic class that works with different types
- Explain the difference between checked and unchecked exceptions
- Create a simple two-thread program that shares data safely
Phase 4: Modern Java
Goal: Write idiomatic, modern Java code using the language's latest features.
This phase covers the features that distinguish modern Java from "your father's Java." These aren't advanced—they're the new baseline.
4.1 Collections Framework
Collections are the containers you use every day. You must understand these before learning Streams, because streams operate on collections.
-
Collection Interfaces:
List,Set,Queue,Deque,Map -
Collection Classes:
ArrayList,LinkedList,HashSet,TreeSet,HashMap,TreeMap,PriorityQueue,ArrayDeque -
Iterators and
ListIterator - Immutable Collections (
List.of(),Set.of(),Map.of())
Why Collections before Streams?
Because you can't understand list.stream().filter(...).collect(...) if you don't understand what a List is. Streams operate on collections. Learn the containers first.
4.2 Records and Sealed Classes
Records eliminate boilerplate for data classes. Sealed classes give you control over inheritance hierarchies.
- Records (compact constructors, canonical constructors, custom methods)
-
Sealed Classes (
sealed,permits,non-sealed,final)
4.3 Pattern Matching
Pattern matching makes your code more expressive and eliminates many explicit casts.
instanceofPattern Matching- Pattern Matching in
switch - Record Patterns
- Guarded Patterns (
whenclause)
4.4 Text Blocks and String Enhancements
Multi-line strings are finally readable in Java.
- Text Blocks (multi-line strings)
- String
formatted()method - String
indent(),stripIndent(),translateEscapes()
4.5 Lambda Expressions
Lambdas let you treat functions as values. They're the foundation of functional programming in Java.
- Lambda Expression Syntax
-
Functional Interfaces (
@FunctionalInterface) - Built-in Functional Interfaces:
Predicate,Function,Consumer,Supplier,BiFunction -
Method References (
::operator)
4.6 Stream API
Streams let you process collections declaratively. They're one of the most powerful features in modern Java.
- Introduction to Streams
-
Creating Streams (
stream(),of(),generate(),iterate()) - Intermediate Operations (
filter(),map(),flatMap(),sorted(),distinct(),limit(),skip()) - Terminal Operations (
forEach(),collect(),reduce(),count(),findFirst(),findAny(),anyMatch(),allMatch(),noneMatch()) -
Collectors (
toList(),toSet(),toMap(),groupingBy(),partitioningBy()) - Parallel Streams
4.7 Optional
Optional helps you handle null values safely and expressively.
- The
Optionalclass - Creating Optionals (
of(),ofNullable(),empty()) - Checking and Retrieving (
isPresent(),isEmpty(),get(),orElse(),orElseGet(),orElseThrow()) - Transforming (
map(),flatMap(),filter())
4.8 Modern Concurrency (Java 21+)
Java's concurrency model has evolved dramatically. Virtual threads change everything about how we think about concurrent programming.
- Virtual Threads (stable since Java 21, Project Loom)
-
Structured Concurrency (
StructuredTaskScope) — Note: Still in preview as of Java 25 (JEP 505) - Scoped Values (finalized in Java 25, replacement for ThreadLocal)
CompletableFuture
4.9 Date-Time API
The modern Date-Time API is immutable, thread-safe, and actually makes sense.
Practice: Complete Exercism's "Streams", "Optionals", and "Date-Time" exercises.
Phase Complete Checkpoint
Before moving to Phase 5, you should be able to:
- Use streams to filter, transform, and collect data
- Create a record class and explain its advantages over a regular class
- Use Optional to handle potentially null values
- Explain when to use virtual threads vs traditional threads
Phase 5: Data & Persistence
Goal: Store and retrieve data professionally.
A Java developer who can't work with databases is unemployable in 2026. This phase is not optional.
5.1 SQL Fundamentals
- DDL:
CREATE,ALTER,DROP - DML:
SELECT,INSERT,UPDATE,DELETE -
WHERE,ORDER BY,GROUP BY,HAVING -
JOINoperations (INNER, LEFT, RIGHT, FULL) - Aggregate functions (
COUNT,SUM,AVG,MIN,MAX) - Subqueries and Common Table Expressions (CTEs)
5.2 JDBC
- JDBC Overview
-
DriverManagerand database connections -
Connection,Statement,PreparedStatement -
ResultSetprocessing - Transaction management
- Connection Pooling with HikariCP
5.3 JPA/Hibernate
- Jakarta Persistence (JPA) concepts
- Entity mapping (
@Entity,@Table,@Id,@GeneratedValue) - Field mapping (
@Column,@Transient) - Relationships (
@OneToOne,@OneToMany,@ManyToOne,@ManyToMany) - JPQL (Java Persistence Query Language)
- Criteria API
5.4 Spring Data JPA
- Spring Data JPA Reference
- Repository pattern (
JpaRepository,CrudRepository) - Query methods (method name derivation)
-
@Queryannotation - Pagination and Sorting
Practice: Build a data access layer for your JanSahayak project using Spring Data JPA.
Phase 6: Spring Boot 4 & Beyond
Goal: Build production-grade applications with the latest Spring ecosystem.
6.1 Spring Boot 4 Fundamentals
Spring Boot 4.0 was released on November 20, 2025 and is built on Spring Framework 7. Key features include:
- Modular codebase — smaller, more focused jars
- Null safety with JSpecify — portfolio-wide improvements
- First-class Java 25 support (while retaining Java 17 compatibility)
- API Versioning support out of the box
- HTTP Service Clients — annotate interfaces, get implementations
@HttpExchange(url = "https://api.example.com")
public interface UserService {
@GetExchange("/users/{id}")
User findById(@PathVariable Long id);
@PostExchange("/users")
User create(@RequestBody CreateUserRequest request);
}
6.2 Spring Boot 4 New Features
- RestTestClient: New testing support for REST APIs
-
OpenTelemetry Starter:
spring-boot-starter-opentelemetryfor metrics and traces -
Kotlin Serialization: First-class support with
spring-boot-kotlin-serialization-starter -
Redis Observability: Auto-configured
MicrometerTracingfor Redis operations - Virtual Thread Integration: HTTP clients auto-configured for virtual threads when enabled
- Gradle 9 Support: Build with the latest Gradle
6.3 Major Dependency Upgrades in Spring Boot 4
| Dependency | Version |
|---|---|
| Spring Framework | 7.0 |
| Spring Security | 7.0 |
| Spring Data | 2025.1 |
| Hibernate | 7.1 |
| Jackson | 3.0 |
| Tomcat | 11.0 |
| Jakarta Persistence | 3.2 |
| JUnit | 6.x |
| Testcontainers | 2.0 |
6.4 REST API Development
@RestController- Request mapping (
@GetMapping,@PostMapping,@PutMapping,@DeleteMapping,@PatchMapping) -
@PathVariable,@RequestParam,@RequestBody -
ResponseEntityfor HTTP responses -
API Versioning with
spring.mvc.apiversion.*
6.5 Spring Security 7.0
- Spring Security Reference
- Authentication vs Authorization
-
SecurityFilterChainconfiguration - Password encoding with
BCryptPasswordEncoder - JWT (JSON Web Tokens) basics
- OAuth 2.0 integration
6.6 Spring AI (Mandatory in 2026)
AI integration is no longer optional. Spring AI makes it straightforward.
- Spring AI Reference
-
ChatClientfor LLM interaction - Prompt engineering
- Structured output (entity extraction)
- RAG (Retrieval-Augmented Generation) basics
- Vector stores integration (Pinecone, pgvector, Milvus)
@Service
public class AIAssistantService {
private final ChatClient chatClient;
public AIAssistantService(ChatClient.Builder builder) {
this.chatClient = builder.build();
}
public String explainScheme(String schemeName) {
return chatClient.prompt()
.user("Explain the " + schemeName + " scheme in simple terms")
.call()
.content();
}
}
Practice: Add AI-powered features to your JanSahayak project.
Phase 7: Professional Practices
Goal: Work like a professional developer.
7.1 Testing
Testing is not optional. JUnit 6 is the default in Spring Boot 4.
-
JUnit 6 (
@Test,@BeforeEach,@AfterEach,@DisplayName) - Assertions (
assertEquals,assertTrue,assertThrows,assertAll) -
@ParameterizedTestand data sources -
Mockito for mocking (
@Mock,@InjectMocks,when(),verify()) -
Spring Boot Testing (
@SpringBootTest,@WebMvcTest,@DataJpaTest) - RestTestClient (new in Spring Boot 4)
- Test-Driven Development (TDD) methodology
7.2 Build Tools
-
Maven (
pom.xml, lifecycle phases, plugins) -
Gradle 9 (
build.gradle, tasks, plugins) - Dependency management
- Multi-module projects
7.3 Containerization
- Docker fundamentals (images, containers, layers)
- Writing
Dockerfile(multi-stage builds) - Docker Compose for multi-container applications
- Container registries
7.4 Observability
-
OpenTelemetry with
spring-boot-starter-opentelemetry - Metrics with Micrometer
- Distributed tracing
- Log aggregation
7.5 CI/CD
- GitHub Actions workflows
- Automated testing in pipelines
- Build and artifact generation
- Deployment automation
7.6 Git Workflows
- Git branching strategies
- Pull request workflows
- Code review best practices
- Conventional Commits
-
.gitignoreconfiguration
For Those Who "Already Know Java"
Maybe you've taken a Java course in college. Maybe you've watched tutorials and built small projects. Maybe you can write code that compiles and runs.
But can you:
- Explain why we use encapsulation (without just saying "it's a principle of OOP")?
- Write a Spring Boot 4 REST API from scratch without copying code?
- Debug a
NullPointerExceptionby reading the stack trace, not by adding print statements everywhere? - Write unit tests before writing the code?
- Set up a CI/CD pipeline that automatically tests and deploys your application?
- Use Virtual Threads appropriately in your applications?
- Integrate AI capabilities using Spring AI?
- Explain what happens when you type
java MyAppand press Enter?
If you hesitated on any of these, this roadmap is still for you. Use it to identify your gaps. Skip what you truly know. Double down on what you don't.
Soft Skills Matter
Technical skills get you interviews. Soft skills get you jobs.
Commit Messages: Follow Conventional Commits:
feat: add document validation endpoint
fix: handle null scheme descriptions
docs: update API documentation
refactor: extract validation logic to service
Code Reviews:
- Be kind. The person wrote this code trying their best.
- Be specific. "This could be better" is useless feedback.
- Ask questions instead of making demands. "What was the thinking behind this approach?" beats "This is wrong."
Technical Communication:
- Write README files that actually help people use your code.
- Document your APIs so others don't have to guess.
- When asking for help, provide context: what you tried, what you expected, what actually happened.
The Path Forward
Here's what I want you to do right now:
- Set up your environment — Java 25, IntelliJ IDEA, Git, GitHub account
-
Create a repository — Call it
java-learning-journeyor whatever speaks to you - Write your first program — Use Java 25's simplified syntax
- Commit it — Your journey has officially begun
Then, follow the roadmap. Phase by phase. Don't skip ahead because something looks "too basic." Don't rush because you're anxious about the job market.
The developers who struggle most aren't those who learn slowly — they're those who build on shaky foundations.
A Final Word
The job market is brutal right now. I won't pretend otherwise. The days when knowing Java basics could land you an interview are long gone.
But here's what hasn't changed: companies still need good developers.
They need people who can solve problems, write maintainable code, work in teams, and learn continuously. This roadmap won't make you a developer in 30 days. It won't guarantee you a job. Nothing can.
What it will do is give you the skills, practices, and portfolio that make you genuinely valuable — not just someone who can solve LeetCode problems, but someone who can build real software that solves real problems.
That's worth more than any shortcut.
Now go build something.
Resources
Official Java Resources:
- Dev.java - Learn Java — Primary learning resource
- Oracle Java Documentation
- OpenJDK
- Java 25 JDK Download
- Brian Goetz (Java Language Architect)
Spring Framework:
- Spring.io
- Spring Guides
- Spring Boot 4 Reference
- Spring Framework 7 Reference
- Spring AI Reference
- Spring Initializr
Practice:
Book:
Tools:
Problem Statements:
Divyansh Bhardwaj is a Corporate and Technical Trainer specializing in Java, Spring, and Full-Stack Development. He has trained thousands of developers across educational institutions in India since 2018.
Connect:
GitHub @dbc2201
LinkedIn (https://www.linkedin.com/in/divyansh-bhardwaj-0850b07b/)
Tags: #java #programming #beginners #roadmap #career #springboot #webdev
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