What is a complete list of Core Java interview Topics 2021

1. What is java feature of java?

2. Java variable

- Local Variable

- Instance Variable

- Static Variable

3. Different between JVM, JRE, JDK ?

4. What Is Jit Compiler ?  

5. what is garbage collection ?

6. OOPS Concept :

- Polymorphism

-  Inheritance 

-  Encapsulation

-  Abstraction

-  Association

-  Aggregation

-  Composition

-  Cohision

7. Data Type 

- Primitive Data Type

- Non Primitive Data Type

8. Conditional Statement

* If statement

- If-else statement

- If-else-if statement

- Nasted-if statement

* For loop

- For-each loop

- While loop

- Do while loop

9. Type Casting

- Implicit type casting

- Explicit type casting

10. Operator

- Arithmetic

- Binary

- Logical

- Compression

- Bitwise

11. Exception

- Exception Handling

    - Checked Exception

    - Unchecked Exception

12. Access modifier 

- Public 

- Protected

- Default

- Private

13. Serialization

- Thread Serialization

- Process Serialization

13.1. DeSerialization

14. Design patterns

- Ceational Design patterns

        - Singleton pattern

        - Prototype pattern

- Structural Design patterns

        - Facade Pattern

- Behavioral Design Pattern

        - Observer Pattern

15. Boxing 

- Auto Boxing

- Un Boxing

15.1.  I/O (Input Output) Stream ? 

16. Different between String , String Buffer, String Builder ?

17. Different between This and Super ?

18. Different between Hash Map And Hash Table ?

19. Different between Abstract Class and Interface ?

20. What is String pool ?

21. What is class Loader ?

22. what is collection framework ?

23. Different between List , Set , Queue ?

24.  what is ArrayList, Linked List, Vector ?

25. What is Priority Queue and Array Deque ?

26. what is HashSet ,LinkedHashSet, TreeSet ?

27. What is Iterator ?

28. What is ORM(Object Relational Mapping) ?

29. What is JPA(Java Persistence API) ? 

30. Web Services

- SOAP Web Services

- REST Web Services