To become a skilled Java developer, you need to gain expertise in a range of technologies, frameworks, and best practices. Here’s a roadmap to help you navigate the key skills and concepts:

• Java and its features. Why learn java ?
• Install Java Development Kit (JDK) and set up an IDE (e.g., IntelliJ IDEA, Eclipse, or VS Code)
• First Java Program and its internals
• JDK , JVM , JRE
• Why is JAVA Platform Independent or WORA (Write once run anywhere)

• Variables and Data Types (int, float, double, char, boolean, String)
• Operators (Arithmetic, Relational, Logical, Bitwise)
• Control Flow Statements (if-else, switch)
• Loops (for, while, do-while)
• Arrays and Strings

• Must Do – Questions to revise and practice
• Option – Questions for further practice
• Revision

• Classes and Objects
• Constructors
• Methods and Method Overloading
• Inheritance (Single, Multilevel, Hierarchical)
• Polymorphism (Method Overriding and Overloading)
• Abstraction (Abstract Classes & Interfaces)
• Encapsulation

✅ Try, Catch, Finally
✅ Throw and Throws
✅ Custom Exceptions

✅ List (ArrayList, LinkedList, Vector)
✅ Set (HashSet, TreeSet)
✅ Map (HashMap, LinkedHashMap, TreeMap)
✅ Queue (PriorityQueue, Deque)

✅ Thread Class and Runnable Interface
✅ Synchronization and Locks
✅ Executors and Thread Pool

✅ Reading and Writing Files (BufferedReader, FileWriter)
✅ Serialization and Deserialization

✅ Lambda Expressions
✅ Streams API
✅ Functional Interfaces (Predicate, Consumer, Supplier)
✅ Optional Class

✅ Connecting Java with MySQL/PostgreSQL
✅ CRUD Operations
✅ ORM Frameworks (Hibernate, JPA)

✅ Servlets and JSP
✅ Spring Boot Framework
✅ RESTful APIs

✅ Maven / Gradle
✅ Git & GitHub

✅ Design Patterns (Singleton, Factory, Observer)
✅ Microservices with Spring Boot
✅ Cloud Computing (AWS, Docker, Kubernetes)
✅ Java Performance Optimization

Now you have mastred java , next step is to build some real world project. You can use all the concepts and build your end to end project. But that would be time consuming as there are many aspect of a real world project.

Better approach would be to learn and framework and use it. I have SpringBoot is one such java based framework which could be used to build any kind of application. It has wide industry adoption.

I have prepared as similar roadmap for SpringBoot. Check it here – SpringBoot RoadMap

You can also check all the article curated on this page – SpringBoot All