Abstract Classes

In Java, an abstract class is a class that cannot be instantiated on its own and must be subclassed. It serves as a blueprint for other classes, providing a common interface and shared implementation. Abstract classes are declared with the abstract keyword.

Abstract Methods

An abstract class can contain abstract methods, which are methods that are declared without an implementation. Subclasses are required to provide an implementation for these methods.

public abstract class Animal {
    // Abstract method (does not have a body)
    public abstract void makeSound();

    // Regular method
    public void sleep() {
        System.out.println("Zzz");
    }
}

Subclassing an Abstract Class

To use an abstract class, you must create a subclass that extends it. The subclass must provide an implementation for all of the abstract methods in the parent class.

public class Dog extends Animal {
    public void makeSound() {
        System.out.println("Woof");
    }
}