What is an abstract class in Java?

What is an abstract class in Java?

An abstract class in Java is a class that cannot be instantiated and can contain abstract methods that must be implemented by subclasses.

Can you give me an example of an abstract class?

Sure! Here's a simple example:

abstract class Animal {
    abstract void sound();
}

class Dog extends Animal {
    void sound() {
        System.out.println("Bark");
    }
}

In this example, Animal is an abstract class with an abstract method sound().

What happens if a subclass does not implement the abstract method?

If a subclass does not implement the abstract method, it must also be declared as abstract, or it will result in a compilation error.

Can an abstract class have concrete methods?

Yes, an abstract class can have both abstract methods and concrete methods (methods with a body). This allows you to provide some default behavior.