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Java Course — 22 Topics, Interview-Ready

A free, beginner-to-advanced Java course covering everything a backend developer needs: syntax, OOP, exception handling, the Collections Framework, generics, lambdas, the Streams API, multithreading and JVM internals — with runnable code examples, common mistakes and real Java interview questions for every topic.

🚀 Start the course — Introduction to Java

📚 Full curriculum

  1. 01
    Introduction to Java — What It Is, JDK vs JRE vs JVM
    Beginner⏱️ 7 min🎯 5 interview Qs
  2. 02⚙️
    How to Install the JDK and Run Your First Java Program
    Beginner⏱️ 6 min🎯 4 interview Qs
  3. 03📦
    Java Variables and Data Types — Primitives vs Reference Types
    Beginner⏱️ 9 min🎯 5 interview Qs
  4. 04
    Java Operators — Arithmetic, Relational, Logical and Bitwise
    Beginner⏱️ 7 min🎯 4 interview Qs
  5. 05🔀
    Java Control Flow — if/else, switch, for, while Loops
    Beginner⏱️ 8 min🎯 4 interview Qs
  6. 06🎯
    Java Methods — Parameters, Overloading, Varargs and Recursion
    Beginner⏱️ 9 min🎯 5 interview Qs
  7. 07📋
    Java Arrays — 1D, 2D, Initialization and Common Operations
    Beginner⏱️ 8 min🎯 4 interview Qs
  8. 08🔤
    Java Strings — String, StringBuilder and Immutability
    Beginner⏱️ 10 min🎯 5 interview Qs
  9. 09🏛️
    Java Classes and Objects — OOP Fundamentals
    Intermediate⏱️ 11 min🎯 5 interview Qs
  10. 10🔒
    Encapsulation in Java — Access Modifiers and Getters/Setters
    Intermediate⏱️ 8 min🎯 4 interview Qs
  11. 11🧬
    Inheritance in Java — extends, super and Method Overriding
    Intermediate⏱️ 10 min🎯 5 interview Qs
  12. 12🎭
    Polymorphism in Java — Dynamic Dispatch and Upcasting
    Advanced⏱️ 9 min🎯 5 interview Qs
  13. 13🪞
    Abstraction in Java — Abstract Classes vs Interfaces
    Advanced⏱️ 11 min🎯 5 interview Qs
  14. 14🔧
    Java Constructors, static and final Keywords Explained
    Intermediate⏱️ 9 min🎯 5 interview Qs
  15. 15⚠️
    Java Exception Handling — try/catch, Checked vs Unchecked
    Intermediate⏱️ 11 min🎯 5 interview Qs
  16. 16📚
    Java Collections Framework — List, Set, Map, Queue
    Intermediate⏱️ 13 min🎯 5 interview Qs
  17. 17🧰
    Java Generics — Type Safety, Wildcards and Bounded Types
    Advanced⏱️ 10 min🎯 5 interview Qs
  18. 18λ
    Java Lambda Expressions and Functional Interfaces
    Advanced⏱️ 9 min🎯 5 interview Qs
  19. 19🌊
    Java Streams API — map, filter, reduce and Collectors
    Advanced⏱️ 12 min🎯 5 interview Qs
  20. 20🧵
    Java Multithreading and Concurrency — Threads, synchronized, Executors
    Advanced⏱️ 13 min🎯 5 interview Qs
  21. 21📂
    Java File I/O — Reading and Writing Files with java.nio
    Intermediate⏱️ 9 min🎯 4 interview Qs
  22. 22🧠
    JVM Internals — Memory Model, Heap, Stack and Garbage Collection
    Advanced⏱️ 12 min🎯 5 interview Qs