[PDF] abstract class extends abstract class java

abstract classes can't be instantiated, only subclassed. other classes extend abstract classes. can have both abstract and concrete methods. similar to interfaces, but (1) can implement methods, (2) fields can have various access modifiers, and (3) subclasses can only extend one abstract class.
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  • Can an abstract class extend an abstract class?

    And an abstract class cannot be instantiated, only extended. An abstract class can extend another abstract class. And any concrete subclasses must ensure that all abstract methods are implemented. Abstract classes can themselves have concrete implementations of methods.

  • Can abstract class implement abstract class?

    An abstract method doesn't have any implementation (method body). A class containing abstract methods should also be abstract. We cannot create objects of an abstract class. To implement features of an abstract class, we inherit subclasses from it and create objects of the subclass.

  • Can abstract classes extend each other?

    A class can implement multiple interfaces. A class can extend only one abstract class.
  • I earlier learned that abstract class can extend concrete class. Though I don't see the reason for it from JAVA designers, but it is ok. I also learned that abstract class that extends concrete class can make overriden methods abstract.
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