[Solved] What will happen if a subclass does not implement all abstract methods of its abstract superclass? — Ans: The subclass must be declared abstract or it causes a compile-time error | Java

Java - Abstraction

What will happen if a subclass does not implement all abstract methods of its abstract superclass?

AThe program will run but throw runtime exceptions

BThe subclass will inherit default implementations automatically

CThe subclass must be declared abstract or it causes a compile-time error

DThe subclass can implement methods later at runtime

Step-by-Step Solution

Solution:

Step 1: Recall rules for abstract methods in subclasses
If a subclass does not implement all abstract methods, it must be abstract itself.
Step 2: Understand consequences of not declaring abstract
If not declared abstract, compiler error occurs.
Final Answer:
The subclass must be declared abstract or it causes a compile-time error -> Option C
Quick Check:
Unimplemented abstract methods require subclass to be abstract [OK]

Quick Trick: Unimplemented abstract methods force subclass to be abstract [OK]

Common Mistakes:

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What will happen if a subclass does not implement all abstract methods of its abstract superclass?