Are abstract classes extended or implemented?

An abstract class will contain abstract methods that do not have an implementation. When you extend this class, sometimes you may decide only to provide implementations for some of those abstract methods . In this case you’ve extended an abstract class and yet the subclass is still abstract.

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Abstract classes cannot be instantiated, but they can be subclassed . When an abstract class is subclassed, the subclass usually provides implementations for all of the abstract methods in its parent class.

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