Polymorphism in Java: How Does it Differ from Overriding and Overloading?

Polymorphism: Unveiling the Distinction from Overriding and Overloading

When it comes to polymorphism in Java, it's important to clarify the difference from overriding and overloading. Overloading refers to the existence of multiple methods with the same name but different parameter lists within the same class. Overriding, on the other hand, involves defining a method in a subclass that has the same signature (name and parameters) as a method in its superclass.

When considering polymorphism, the most accurate answer lies in the concept of abstract classes or interfaces. An abstract base class defines a method without an implementation, which is then implemented in its subclasses. This approach exemplifies polymorphism.

To illustrate, consider an abstract base class Human with an abstract method goPee(), which cannot be defined at the Human level but must be implemented in the subclasses Male and Female to accommodate gender-specific behavior.

public abstract class Human {
    public abstract void goPee();
}

public class Male extends Human {
    @Override
    public void goPee() {
        System.out.println("Stand Up");
    }
}

public class Female extends Human {
    @Override
    public void goPee() {
        System.out.println("Sit Down");
    }
}

In this example, the method goPee() is overridden in the subclasses to provide specific implementations. Polymorphism comes into play when we can tell a group of Humans to go pee, and they will perform the action according to their respective implementations.

public static void main(String[] args) {
    ArrayList<Human> group = new ArrayList<>();
    group.add(new Male());
    group.add(new Female());

    // Tell Humans to go pee
    for (Human person : group) person.goPee();
}

Output:

Stand Up
Sit Down

From this demonstration, it becomes clear that polymorphism is the ability for different objects within an inheritance hierarchy to exhibit different behaviors while responding to the same message. Overriding is the mechanism that enables this behavior, while overloading is a separate concept related to method signatures within the same class.

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