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Java Programming Tutorial - 58 - Abstract and Concrete Classes Video Lecture | Java Programming Fundamentals: For Beginners - Back-End Programming

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FAQs on Java Programming Tutorial - 58 - Abstract and Concrete Classes Video Lecture - Java Programming Fundamentals: For Beginners - Back-End Programming

1. What is an abstract class in Java?
Ans. An abstract class in Java is a class that cannot be instantiated and is used as a base for other classes. It can contain both abstract and non-abstract methods, and it provides a common interface for its subclasses.
2. How is an abstract class different from a concrete class in Java?
Ans. A concrete class in Java is a class that can be instantiated, whereas an abstract class cannot be directly instantiated. Concrete classes can be directly used to create objects, while abstract classes need to be extended by other classes before they can be used to create objects.
3. Can an abstract class have a constructor in Java?
Ans. Yes, an abstract class can have a constructor in Java. However, the constructor of an abstract class is usually used to initialize the variables and state of the abstract class itself, rather than creating instances of the abstract class.
4. Can a concrete class extend multiple abstract classes in Java?
Ans. No, a concrete class in Java can only extend one abstract class. Java does not support multiple inheritance for classes, so a class can only have a single direct superclass.
5. Can an abstract class have non-abstract methods in Java?
Ans. Yes, an abstract class in Java can have both abstract and non-abstract methods. Non-abstract methods in an abstract class can have a complete implementation and can be directly used by the subclasses without overriding them.
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