Interfaces and Abstract Classes Interview Questions | OOPS | NextRound

1What is an Abstract Class? When is it used?Intermediate

2What is an Interface? When is it used?Intermediate

3Compare Abstract Classes and Interfaces. When would you choose one over the other?Intermediate

4Can an Interface have fields? Why or why not?Intermediate

5Can an Interface have a Constructor?Intermediate

6What are Default Methods in Interfaces (Java 8+ / C# 8+)? Why were they introduced?Intermediate

7Can an Interface inherit from another Interface?Intermediate

8Can an Abstract Class implement an Interface and not define all methods?Intermediate

9What are Marker Interfaces (e.g., Serializable)? Are they an anti-pattern?Intermediate

10How do you achieve Loose Coupling using Interfaces? (Dependency Injection basics)Intermediate

11What is 'Programming to an Interface, not an Implementation'?Intermediate

12Why can't you instantiate an Interface or Abstract Class?Intermediate

13Explain "Explicit Interface Implementation" (C#) and when it's needed.Intermediate