100+ Java OOPs Interview Questions for Freshers

In this article, we will provide you with a list of frequently asked Java OOPs interview questions for freshers. Java is a widely used object-oriented programming language. It is used to develop web applications, mobile applications, enterprise applications, and more. If you are a fresher looking to get into Java development, you need to have a good understanding of object-oriented programming concepts.

Introduction

Java is a widely used object-oriented programming language. It is used to develop web applications, mobile applications, enterprise applications, and more. If you are a fresher looking to get into Java development, you need to have a good understanding of object-oriented programming concepts. In this article, we will provide you with a list of frequently asked Java OOPs interview questions for freshers.

What is Object-Oriented Programming

Object-Oriented Programming (OOP) is a programming paradigm based on the concept of “objects”. Objects are instances of classes that contain data and methods that manipulate the data. OOP focuses on the concept of “encapsulation”, which means that the data and methods of an object are hidden from the outside world and can only be accessed through public methods.

Java OOPs interview questions for freshers

1. What is OOPs?
2. What are the pillars of OOPs?
3. What is Inheritance?
4. What is Polymorphism?
5. What is Abstraction?
6. What is Encapsulation?
7. What are Access Modifiers?
8. What is a Constructor?
9. What is a Destructor?
10. What is an Interface?
11. What is an Abstract Class?
12. What is a Package?
13. What is a Static variable?
14. What is a Static method?
15. What is the difference between Static and Non-Static methods?
16. What is a Final variable?
17. What is a Final method?
18. What is a Final class?
19. What is the difference between an Interface and an Abstract class?
20. What is a Superclass?
21. What is a Subclass?
22. What is Method Overloading?
23. What is Method Overriding?
24. What is the difference between Method Overloading and Method Overriding?
25. What is a Constructor Overloading?
26. What is a Constructor Chaining?
27. What is a Default Constructor?
28. What is a Parameterized Constructor?
29. What is the difference between a Constructor and a Method?
30. What is a Class?
31. What is an Object?
32. What is a Reference Variable?
33. What is the difference between an Object and a Reference Variable?
34. What is a Garbage Collector?
35. What is a Memory Leak?
36. What is a Stack and Heap Memory?
37. What is the difference between a Stack and a Heap Memory?
38. What is a Class Loader?
39. What is a JVM (Java Virtual Machine)?
40. What is the purpose of the main() method in Java?
41. What is the difference between a public and a private access modifier?
42. What is a Protected access modifier?
43. What is a Default access modifier?
44. What is a Singleton Class?
45. What is a Multithreaded environment?
46. What is Synchronization?
47. What is Deadlock?
48. What is a Thread?
49. What is a Runnable Interface?
50. What is the difference between a Thread and a Runnable Interface?
51. What is a Thread Pool?
52. What is an Executor Framework?
53. What is the difference between a Checked and an Unchecked Exception?
54. What is a Try-Catch block?
55. What is a Finally block?
56. What is a Throws keyword?
57. What is a Throw keyword?
58. What is a Exception Handling in Java?
59. What is a Java Collection Framework?
60. What is an ArrayList?
61. What is a LinkedList?
62. What is a HashSet?
63. What is a TreeSet?
64. What is a HashMap?
65. What is a TreeMap?
66. What is a Queue Interface?
67. What is a Stack Interface?
68. What is a Set Interface?
69. What is a List Interface?
70. What is a Map Interface?
71. What is a Comparator Interface?
72. What is an Iterator Interface?
73. What is a Iterable Interface?
74. What is the difference between a List and a Set?
75. What is the difference between a HashMap and a Hashtable?
76. What is the difference between a Vector and an ArrayList?
77. What is the difference between an Iterator and a ListIterator?
78. What is a Reflection API?
79. What is a Marker Interface?
80. What is an Inner Class?
81. What is a Nested Class?
82. What is a Local Inner Class?
83. What is an Anonymous Inner Class?
84. What is a Static Nested Class?
85. What is a Method Reference?
86. What is a Lambda Expression?
87. What is the difference between a Lambda Expression and an Anonymous Inner Class?
88. What is a Functional Interface?
89. What is the difference between a Checked and an Unchecked Exception?
90. What is a RuntimeException?
91. What is an Error?
92. What is the difference between an Error and an Exception?
93. What is a StackTrace?
94. What is a Thread dump?
95. What is a ClassCastException?
96. What is a NullPointerException?
97. What is a ConcurrentModificationException?
98. What is a ClassNotFoundException?
99. What is a NoClassDefFoundError?
100. What is a ClassNotFoundException vs NoClassDefFoundError?

Conclusion

Object-Oriented Programming is an important concept in Java development. Freshers need to have a good understanding of OOP concepts to crack Java OOPs interviews. We hope that this article has provided you with a good understanding of frequently asked Java OOPs interview questions for freshers.

FAQs

1. What is Object-Oriented Programming?
2. What are the key features of Object-Oriented Programming?
3. What is a Class in Java?
4. What is an Object in Java?
5. What is Inheritance in Java?
6. What is Polymorphism in Java?
7. What is Encapsulation in Java?
8. What is Abstraction in Java?
9. What are the Access Modifiers in Java?
10. What is Method Overloading in Java?
11. What is Method Overriding in Java?
12. What is the Difference between Method Overloading and Method Overriding?
13. What is the super keyword in Java?
14. How can I prepare for Java OOPs interviews?
15. What is the importance of OOP in Java development?

I hope these 100 Java OOPs interview questions will help you prepare well for your Java OOPS interview. Good luck!