📍 Java Basics
1. What is Java?
2. JVM, JRE, JDK — know their roles and differences
3. Data Types & Variables — primitives, reference types
4. Operators — arithmetic, relational, logical
5. Type Casting — implicit and explicit
📍 Control Flow
6. if-else statements
7. switch-case syntax and use-cases
8. Loops: for, while, do-while
9. break & continue — control loop behavior
10. Ternary operator (?:) — compact conditional
📍 OOP Concepts
11. Class & Object — blueprint and instances
12. Inheritance — code reuse and is-a relationship
13. Polymorphism — compile-time (overloading) & runtime (overriding)
14. Abstraction — hiding implementation details
15. Encapsulation — data hiding with access modifiers
📍 Core OOP in Java
16. Method Overloading — same method name, different params
17. Method Overriding — subclass modifies superclass method
18. Constructors & Constructor Overloading
19.
this and super keywords — referencing current and parent class 20. Static keyword — class-level variables and methods
📍 Exception Handling
21. try-catch-finally blocks
22. throw vs throws — raising vs declaring exceptions
23. Checked vs Unchecked Exceptions
24. Custom Exceptions — user-defined error handling
25. Common exceptions like NullPointerException, ArrayIndexOutOfBoundsException
📍 Collections Framework
26. List, Set, Map interfaces
27. ArrayList vs LinkedList — pros & cons
28. HashSet vs TreeSet — unordered vs sorted sets
29. HashMap vs TreeMap — unordered vs sorted maps
30. Iterator & enhanced for-loop for traversing collections
📍 Strings & Arrays
31. String vs StringBuilder vs StringBuffer — immutability and performance
32. Common String methods (substring, equals, indexOf)
33. 1D & 2D Arrays — declaration and traversal
34. Array vs ArrayList — fixed vs dynamic size
35. String immutability — benefits and implications
📍 Advanced Java
36. Interfaces & Abstract Classes — design contracts and partial implementation
37. Lambda Expressions — functional programming style
38. Functional Interfaces — single abstract method interfaces
39. Streams API — processing collections declaratively
40. File I/O with FileReader, BufferedReader
📍 Multithreading & Concurrency
41. Thread class vs Runnable interface
42. Thread Lifecycle (New, Runnable, Running, Waiting, Terminated)
43. Synchronization — thread safety techniques
44. wait(), notify(), notifyAll() — inter-thread communication
45. Executor Framework — managing thread pools
📍 Best Practices & Tools
46. Writing Clean Code — naming, formatting, SOLID principles
47. Java Memory Model — Heap vs Stack
48. Garbage Collection basics — automatic memory management
49. Unit Testing with JUnit
50. Version Control — Git & GitHub basics
💡 Pro Tip: Understand these concepts well, back answers with code examples, and relate them to real projects in interviews.
❤️ Tap ❤️ if you found this helpful!