Object Oriented Programming Interview Questions

1. What is Polymorphism in OOP?

2. Difference Between Abstraction and Encapsulation

3. What are the Four Pillars of OOP?

4. Difference Between Interface and Abstract Class

5. Composition vs Inheritance in OOP

6. What are SOLID Principles?

7. What is Inheritance in OOP?

8. Method Overloading vs Overriding

9. What is Encapsulation in OOP?

10. What is a Constructor in OOP?

11. What is Abstraction in OOP?

12. What is a Design Pattern?

13. What is the Singleton Pattern?

14. What is the Factory Pattern?

15. What is Dependency Injection?

16. Static vs Instance Methods: What is the Difference?

17. What is Method Overriding in OOP?

18. What is Coupling and Cohesion in OOP?

19. What is the Observer Pattern?

20. What is a Virtual Function?

21. Aggregation vs Composition in OOP

22. What is the Liskov Substitution Principle?

23. What is the Strategy Pattern?

24. What is Multiple Inheritance?

25. What is a Copy Constructor?

26. What is the Open-Closed Principle?

27. What is the Builder Pattern?

28. What is the Prototype Pattern?

29. What is the Adapter Pattern?

30. What is the Bridge Pattern?

31. What is the Composite Pattern?

32. What is the Decorator Pattern?

33. What is the Facade Pattern?

34. What is the Flyweight Pattern?

35. What is the Proxy Pattern?

36. What is the Chain of Responsibility Pattern?

37. What is the Command Pattern?

38. What is the Interpreter Pattern?

39. What is the Iterator Pattern?

40. What is the Mediator Pattern?

41. What is the Memento Pattern?

42. What is the State Pattern?

43. What is the Template Method Pattern?

44. What is the Visitor Pattern?

45. Creational vs Structural vs Behavioral Patterns

46. What is the Single Responsibility Principle?

47. What is the Interface Segregation Principle?

48. What is the Dependency Inversion Principle?

49. Explain SOLID Principles with Real-World Examples

50. Abstract Class vs Interface: When to Use Which?

51. What is Method Hiding in OOP?

52. Covariance and Contravariance Explained

53. What Are Generics in Java?

54. What Are Templates in C++?

55. Generics vs Templates: Java vs C++

56. What is Immutability in OOP?

57. Value Semantics vs Reference Semantics

58. Object Equality vs Identity

59. The hashCode() and equals() Contract

60. What is a Destructor in OOP?

61. What is a Finalizer in OOP?

62. What is RAII (Resource Acquisition Is Initialization)?

63. What are Mixins in Object-Oriented Programming?

64. What are Traits in Object-Oriented Programming?

65. Mixins vs Traits vs Interfaces: What is the Difference?

66. What is Duck Typing in Object-Oriented Programming?

67. What is Delegation in OOP?

68. What is the Law of Demeter?

69. What is the DRY Principle?

70. What is the KISS Principle?

71. What is the YAGNI Principle?

72. What is the God Object Anti-Pattern?

73. What is Spaghetti Code?

74. What Are Common OOP Anti-Patterns?

75. What is the Anemic Domain Model Anti-Pattern?

76. What is the Circular Dependency Anti-Pattern?

77. What are the Types of Dependency Injection?

78. Constructor Injection vs Setter Injection

79. What is an IoC Container?

80. Dependency Injection vs Service Locator

81. What is Inversion of Control?

82. UML Class Diagram Relationships Explained

83. Association vs Aggregation vs Composition

84. What is a UML Sequence Diagram?

85. Class vs Object Explained

86. What is the “this” Keyword?

87. What is the self Keyword in Python?

88. What Does super Do in OOP?

89. What Are Access Modifiers?

90. Public vs Private vs Protected

91. What is a Sealed Class?

92. What is a Final Class in OOP?

93. What is a Nested Class in OOP?

94. What is an Inner Class in OOP?

95. What is an Anonymous Class in OOP?

96. What is Operator Overloading in OOP?

97. How Does Garbage Collection Relate to OOP?

98. What is a Smart Pointer?

99. RAII vs Garbage Collection

100. What is a Shallow Copy?

101. What is a Deep Copy?

102. Shallow Copy vs Deep Copy

103. What is the clone() Method?

104. What is Object Cloning?

105. What is a Static Class?

106. What is a Utility Class?

107. What is a Companion Object?

108. What is a Data Class?

109. What is a Record Type?

110. What is a Value Object?

111. What is an Entity vs a Value Object?

112. What is a Domain Model in OOP?

113. What is a Fluent Interface in OOP?

114. What is Method Chaining in OOP?

115. What is a Marker Interface in OOP?

116. What is a Functional Interface in OOP?

117. What is a Lambda Expression in OOP?

118. What are Default Methods in Interfaces?

119. What are Static Methods in Interfaces?

120. What is the Diamond Problem in Multiple Inheritance?

121. How Does Java Avoid the Diamond Problem?

122. What is an Interface Default Method Conflict?

123. What is a Tightly Coupled System?

124. What is a Loosely Coupled System?

125. High Cohesion vs Low Cohesion

126. What is the Single Table Inheritance Pattern?

127. What is the Class Table Inheritance Pattern?

128. What is Polymorphic Dispatch?

129. Static Binding vs Dynamic Binding

130. Early Binding vs Late Binding

131. What is a Vtable (Virtual Method Table)?

132. How Do Virtual Method Tables (vtables) Work?

133. What is Name Mangling?

134. What is Function Overriding vs Shadowing?

135. What is a Pure Virtual Function?

136. What is an Abstract Method?

137. Concrete Class vs Abstract Class

138. What is a Template Class?

139. What is a Generic Class?

140. Bounded Type Parameters Explained

141. What is Type Erasure?

142. What is a Wildcard Generic in Java?

143. What is a Mutator Method in OOP?

144. What is an Accessor Method in OOP?

145. Getters and Setters: Best Practices

146. What is the Tell, Don’t Ask Principle?

147. What is the Composite Reuse Principle?

148. Why Favor Composition Over Inheritance?

149. Liskov Substitution Violation: A Concrete Example

150. What is a Code Smell?

151. What is Refactoring in OOP?

152. What is the Extract Method Refactoring?

153. What is Replace Conditional with Polymorphism?

154. What is Design by Contract?

155. What is an Invariant in OOP?

156. What are Preconditions and Postconditions?

157. What is a Class Invariant?

158. What is an Encapsulation Violation?

159. What is Information Hiding?

160. Information Hiding vs Encapsulation

161. Facade vs Adapter Pattern

162. Adapter vs Bridge Pattern

163. Decorator vs Proxy Pattern

164. Strategy vs State Pattern

165. Factory Method vs Abstract Factory

166. What is the Abstract Factory Pattern?

167. Factory Pattern vs Builder Pattern

168. Singleton vs Static Class

169. Thread Safety in the Singleton Pattern

170. What is a Thread-Safe Singleton?

171. What is Lazy Initialization in OOP?

172. Eager vs Lazy Initialization in OOP

173. What is Object Pooling?

174. The Object Pool Design Pattern Explained

175. What is the Null Object Pattern?

176. What is the Specification Pattern?

177. What is the Repository Pattern?

178. What is the Unit of Work Pattern?

179. What is the Active Record Pattern?

180. Active Record vs Repository Pattern

181. What is the DAO Pattern?

182. DAO vs Repository Pattern

183. What is the MVC Pattern?

184. What is the MVVM Pattern?

185. MVC vs MVVM vs MVP

186. Observer vs Pub/Sub Pattern

187. What is Event-Driven OOP Design?

188. What is a Callback in OOP?

189. What is a Listener Interface?

190. What is Multiple Dispatch?

191. Single Dispatch vs Multiple Dispatch

192. What is Double Dispatch in OOP?

193. How Does the Visitor Pattern Use Double Dispatch?

194. What is a Fat Interface in OOP?

195. What is Interface Pollution in OOP?

196. What is a Role Interface in OOP?

197. Header Interface vs Role Interface

198. What is a Protocol in Swift?

199. Protocols vs Interfaces

200. What is a Trait Conflict?

201. Structural Typing vs Nominal Typing

202. What is Nominal Typing?

203. What is Structural Typing?

204. What is a Companion Object in Kotlin?

205. What is an Extension Method?

206. Extension Methods vs Inheritance

207. What is a Partial Class?

208. What is a Friend Class in C++?

209. Friend Functions vs Encapsulation

210. What is a Static Initializer Block?

211. What is an Instance Initializer Block?

212. What is Constructor Chaining? Explained

213. this() Constructor Call vs super() Constructor Call

214. What is Constructor Overloading?

215. What is the Telescoping Constructor Anti-Pattern?

216. Builder Pattern vs Telescoping Constructor

217. What is a Private Constructor?

218. What is a Protected Constructor?

219. What is a Copy Assignment Operator?

220. Move Semantics vs Copy Semantics

221. What is a Move Constructor?

222. What is the Rule of Three in C++?

223. What is the Rule of Five in C++?

224. What is Object Slicing in C++?

225. What is a Hook in the Template Method Pattern?

226. What is a Hollow Abstraction in OOP?