Mastering Java: The Ultimate Quiz for 'Thinking in Java'

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Mastering Java: The Ultimate Quiz for 'Thinking in Java'. Dive deep into Java with multiple-choice questions. Challenge yourself with quiz questions designed to test and improve your understanding of the 'Thinking in Java' book. Get ready for your exam!

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What must classes do to conform to an interface?

Declare all interface fields
Implement all abstract methods
Extend another concrete class
Provide default implementations

The correct answer is: Implement all abstract methods

Classes that implement an interface must provide implementations for all of the abstract methods declared in the interface. Option A is incorrect because interfaces do not have fields, they only have method signatures. Option C is incorrect because interfaces cannot be extended, they are implemented. Option D is incorrect because interfaces do not have default implementations, they only provide method signatures. Therefore, the correct answer is B, since implementing all the abstract methods in an interface is a key requirement for classes to conform to an interface.