Core Java Interview Questions for Freshers

Core Java interview questions for freshers cover fundamental concepts such as Java basics, OOP principles, data types, exception handling, collections, multithreading, and JVM concepts. These questions help beginners prepare for entry-level Java developer interviews with confidence.

Java Basics

1. What is Java?
2. Why is Java platform independent?
3. What are the features of Java?
4. What is the difference between JDK, JRE, and JVM?
5. How does Java achieve portability?
6. What is bytecode in Java?
7. What is the main method in Java?
8. Can we run a Java program without the main() method?
9. Why is Java not 100% object-oriented?
10. What are access modifiers in Java?

Data Types & Variables

11. What are primitive data types in Java?
12. Difference between primitive and non-primitive data types
13. What is type casting?
14. Difference between implicit and explicit casting
15. What is a variable?
16. Types of variables in Java
17. What is static variable?
18. Difference between local and instance variables

Operators & Control Statements

19. Types of operators in Java
20. Difference between == and .equals()
21. What is a conditional statement?
22. Difference between if-else and switch
23. What are loops in Java?
24. Difference between for, while, and do-while
25. What is break and continue?

Object-Oriented Programming (OOPs)

26. What is OOP?
27. What is a class?
28. What is an object?
29. Difference between class and object
30. What is inheritance?
31. Types of inheritance in Java
32. What is polymorphism?
33. Difference between method overloading and method overriding
34. What is encapsulation?
35. What is abstraction?
36. Difference between abstract class and interface
37. Can an interface have methods with implementation?
38. What is final keyword?

Constructors & Keywords

39. What is a constructor?
40. Types of constructors
41. Difference between constructor and method
42. What is this keyword?
43. What is super keyword?
44. What is static keyword?
45. Can we override static methods?

Strings & Arrays

46. What is String in Java?
47. Difference between String, StringBuffer, and StringBuilder
48. Why is String immutable?
49. What is an array?
50. Types of arrays in Java
51. Difference between array and ArrayList

Exception Handling

52. What is an exception?
53. Types of exceptions in Java
54. Difference between checked and unchecked exceptions
55. What is try-catch block?
56. What is finally block?
57. Can we have multiple catch blocks?
58. What is throw vs throws?

Multithreading (Basics)

59. What is a thread?
60. Difference between process and thread
61. How to create a thread in Java?
62. What is synchronization?
63. What is sleep() method?

Collections (Basic Level)

64. What is Collection Framework?
65. Difference between List, Set, and Map
66. Difference between ArrayList and LinkedList
67. Difference between HashMap and Hashtable
68. What is Iterator?

Java Miscellaneous

69. What is garbage collection?
70. What is finalize() method?
71. What is wrapper class?
72. Difference between int and Integer
73. What is autoboxing and unboxing?
74. What is package in Java?
75. What is import keyword?
76. What is serialization?
77. Difference between transient and static
78. What is JVM memory structure?
79. What is Java 8 feature you know?
80. What is classloader?

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