An abstract class in Java is a class that cannot be instantiated and may contain abstract methods (without implementation) as well as concrete methods. It forms the foundation for achieving abstraction, encouraging code reuse and enforcing structure in subclasses.
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Which keyword is used to declare an abstract class?
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Question 3 of 15
3. Question
Can abstract classes have constructors?
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Question 4 of 15
4. Question
Which of the following statements is true about abstract classes?
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Question 5 of 15
5. Question
What happens if a class contains an abstract method?
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Question 6 of 15
6. Question
Can abstract methods be static in Java?
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Question 7 of 15
7. Question
What is the output of:
abstract class A { abstract void display(); } class B extends A { void display() { System.out.println(“Hello”); } }
What will happen if `new B().display();` is executed?
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Question 8 of 15
8. Question
Can an abstract class implement an interface?
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Question 9 of 15
9. Question
Can an abstract class extend another abstract class?
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Question 10 of 15
10. Question
Can a class be abstract without any abstract method?
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Question 11 of 15
11. Question
Can we declare an abstract class as `final`?
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Question 12 of 15
12. Question
Which of the following is NOT allowed inside an abstract class?
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Question 13 of 15
13. Question
Which of these is a valid use case for an abstract class?
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Question 14 of 15
14. Question
What is the purpose of abstract classes in Java?
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Question 15 of 15
15. Question
Which of the following is correct syntax for declaring an abstract class?
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Summary
An abstract class in Java acts as a blueprint for its subclasses, enabling partial abstraction and method enforcement. It cannot be instantiated and may include both abstract and concrete methods, making it ideal for designing base-level architecture in OOP design.
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