To add a new method to an existing interface without breaking existing implementations in a language that originally did not support default methods, what is the best strategy?

hard🔁 Follow Up Q10 of Q15

OOP & Design Patterns - Abstraction - Abstract Class vs Interface - When to Use Which

ACreate a new interface that extends the original and adds the method.

BAdd the method directly to the existing interface and update all implementations.

CConvert the interface into an abstract class with the new method implemented.

DRemove the interface and replace it with a concrete class.

Step-by-Step Solution

Solution:

Step 1: Understand interface evolution constraints
Adding methods breaks existing implementations if no default methods.
Step 2: Use interface extension
Create a new interface extending the old one with the new method to avoid breaking code.
Final Answer:
Option A -> Option A
Quick Check:
Extending interfaces preserves backward compatibility [OK]

Quick Trick: Extend interfaces to add methods without breaking code [OK]

Common Mistakes:

MISTAKES

Directly modifying interface breaks existing implementations
Converting to abstract class changes design contract
Replacing interface with concrete class reduces flexibility

Trap Explanation:

PITFALL

Modifying interface directly breaks existing code; abstract class changes design.

Interviewer Note:

CONTEXT

Tests knowledge of interface evolution and backward compatibility strategies.

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More OOP & Design Patterns Quizzes

To add a new method to an existing interface without breaking existing implementations in a language that originally did not support default methods, what is the best strategy?

Step 1: Understand interface evolution constraints

Step 2: Use interface extension

Final Answer:

Quick Check:

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