1. Beginner Level: Core Java

Learn the Basics

• JDK, JRE, JVM – Understand Java’s runtime and development environment

• Syntax & Data Types – Variables, data types, loops, conditionals

• Object-Oriented Programming (OOP) – Classes, objects, inheritance, polymorphism

• Exception Handling – try-catch, finally, custom exceptions

• Basic Input/Output – Console and file I/O using Scanner and FileReader

 Tools: IntelliJ IDEA / Eclipse, VS Code, JDK 17+ 

2. Intermediate Level: Java Collections, Threads, and More

Master Intermediate Concepts

• Collections Framework – List, Set, Map, Queue, Iterator

• Multithreading & Concurrency – Thread, Runnable, ExecutorService

• Java I/O & NIO – Streams, Channels, Buffers

• Lambda Expressions & Functional Interfaces – Java 8 features

• Streams API – Processing data in a functional style

• Date and Time API – LocalDate, LocalTime, DateTimeFormatter

Also Read: Is prompt engineering the future of programming?

3. Advanced Level: Frameworks and Ecosystem

Dive into Enterprise Development

• Java JDBC – Connecting with databases (e.g., MySQL, PostgreSQL)

• Servlets & JSP – Web app foundations

• Spring Framework (Spring Boot) – REST APIs, MVC, Security, Data

• Hibernate/JPA – ORM for database interaction

 Tools: Maven or Gradle, Postman, Git, Docker (for deploying microservices) 

4. Specializations Based on Your Goals

Backend Development

Spring Boot, REST APIs, Microservices architecture

Android Development

Kotlin is preferred now, but Java still used with Android SDK

Big Data

Java with Hadoop, Apache Spark

Security

Learn OAuth2, JWT, HTTPS, secure coding practices

5. Modern Java Practices (2025 Updates)

• Java 21+ features (e.g., Record Patterns, Virtual Threads from Project Loom)

• Modular Programming – Using the Java Platform Module System (JPMS)

• Testing – JUnit 5, Mockito

• CI/CD – GitHub Actions, Jenkins

• Cloud Native – Build containerized apps with Docker and deploy on AWS/GCP

Learning Resources

• Books: Effective Java by Joshua Bloch, Head First Java

• Courses: Coursera (Java Programming & Software Engineering), Udemy (Java Masterclass)

• Practice: LeetCode, HackerRank, Codeforces (for Java competitive programming)

Build real-world projects — a portfolio site, blog engine, or even a small e-commerce backend with Spring Boot + PostgreSQL