When to use abstract class and when should we use interfaces in Java?

Question

Accepted Answer

Abstract classes are used for code reuse and interfaces are used for multiple inheritance and loose coupling.

Abstract classes can have both abstract and non-abstract methods while interfaces can only have abstract methods.
Abstract classes can have constructors while interfaces cannot.
Interfaces are used when a class needs to implement multiple behaviors while abstract classes are used for code reuse.
Interfaces promote loose coupling while abstract classes promote tight coupling.
Example: Abstract class - Animal with common methods for all animals. Interface - Flyable with methods for flying behavior.
Example: Abstract class - Shape with common methods for all shapes. Interface - Drawable with methods for drawing behavior.

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