Difference between interface and abstract class

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Accepted Answer

An abstract class can have both abstract and non-abstract methods, while an interface can only have abstract methods.

An abstract class can have constructors, while an interface cannot.
A class can implement multiple interfaces, but can only inherit from one abstract class.
An abstract class can have instance variables, while an interface cannot.
An abstract class can provide default implementations for some methods, while an interface cannot.
An abstract class is used when a common base implementation is needed, while an interface is used when a common behavior is needed across unrelated classes.

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