Careeroza

Method Overriding

Rules

Overriding means a subclass provides its own version of a method it inherited. The method is chosen at runtime based on the actual object.

RuleDetail
Same signaturesame name and same parameter types
Return typesame, or a subtype (covariant return)
Accesssame or wider (protected → public is ok, public → private is not)
Exceptionscannot throw new or broader checked exceptions
Cannot overridefinal, static and private methods

Overriding with @Override

Example

Each notification type sends in its own way. @Override asks the compiler to check that you really override a parent method.

public class Main {
    public static void main(String[] args) {
        Notification[] list = { new Notification(), new SmsNotification(), new EmailNotification() };
        for (Notification n : list) {
            n.send("Your order is out for delivery");
        }
    }
}

class Notification {
    void send(String msg) {
        System.out.println("[generic] " + msg);
    }
}

class SmsNotification extends Notification {
    @Override
    void send(String msg) {
        System.out.println("[SMS] " + msg.substring(0, 14) + "...");
    }
}

class EmailNotification extends Notification {
    @Override
    void send(String msg) {
        System.out.println("[Email] Subject: Update | Body: " + msg);
    }
}

Output

[generic] Your order is out for delivery
[SMS] Your order is ...
[Email] Subject: Update | Body: Your order is out for delivery

Why @Override Matters

A typo creates a new method instead of overriding. With @Override the compiler catches it.

class Animal {
    void makeSound() { }
}

class Dog extends Animal {
    @Override
    void makesound() { }   // error: method does not override or implement a method from a supertype
}

Tip: Always write @Override. It costs nothing and prevents silent bugs.