In object-oriented programming, dynamic binding refers to the mechanism that allows different methods to be dynamically invoked based on the actual type of the object at runtime. In Java, dynamic binding is achieved through the use of inheritance and polymorphism.

Abstract classes in Java provide a great way to define common behavior for a group of related classes. An abstract class can have both abstract and non-abstract methods.

Let’s take a closer look at how dynamic binding works in the context of abstract classes in Java.

The Abstract Class

To create an abstract class in Java, simply use the abstract keyword before the class declaration. Abstract classes cannot be instantiated directly, but they can be extended by other classes.

Here’s an example of an abstract class called Animal:

public abstract class Animal {
    public abstract void makeSound();
    
    public void breathe() {
        System.out.println("Breathing...");
    }
}

In this example, Animal is an abstract class that has an abstract method makeSound() and a non-abstract method breathe(). The makeSound() method is declared as abstract because we want each concrete subclass to provide its own implementation.

Dynamic Binding with Abstract Methods

When a concrete subclass extends an abstract class, it must provide implementations for all the abstract methods defined in the abstract class. This is where dynamic binding comes into play.

Let’s create a concrete class Dog that extends the Animal abstract class:

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

In this example, Dog is a subclass of Animal and it overrides the makeSound() method to provide its own implementation.

Dynamic Binding at Runtime

Now, let’s see dynamic binding in action:

public class Main {
    public static void main(String[] args) {
        Animal animal = new Dog();
        animal.makeSound(); // Outputs "Woof woof!"
        
        animal = new Cat();
        animal.makeSound(); // Outputs "Meow!"
    }
}

In this example, we create an instance of Dog and assign it to an Animal reference variable. When we invoke the makeSound() method on this object, the overridden makeSound() method in the Dog class is dynamically invoked, so it outputs “Woof woof!”.

Similarly, if we create an instance of Cat and assign it to the same Animal reference variable, the overridden makeSound() method in the Cat class will be dynamically invoked, so it outputs “Meow!”.

Dynamic binding allows us to treat objects of different subclasses in a uniform way by using a common abstract class reference. This flexibility and polymorphism are fundamental concepts in object-oriented programming.

#java #abstractclasses #dynamicbinding