Method Overriding and Dynamic Method Dispatch (Runtime Polymorphism)

Intermediate14 min read•Updated: 2026-10-22

🎪 Method Overriding and Dynamic Method Dispatch

Introduction

Runtime Polymorphism allows a superclass reference variable to refer to a subclass object. When an overridden method is called through that reference, Java resolves the call to the subclass implementation at runtime via Dynamic Method Dispatch.

💻 Upcasting & Dynamic Dispatch in Action

1import java.util.List;
2import java.util.ArrayList;
3 
4class NotificationService {
5    public void send(String recipient, String message) {
6        System.out.printf("[DEFAULT NOTIFICATION] to %s: %s%n", recipient, message);
7    }
8}
9 
10class EmailNotification extends NotificationService {
11    @Override
12    public void send(String recipient, String message) {
13        System.out.printf("[EMAIL DISPATCHED] to %s: %s%n", recipient, message);
14    }
15}
16 
17class SmsNotification extends NotificationService {
18    @Override
19    public void send(String recipient, String message) {
20        System.out.printf("[SMS DISPATCHED via TELECOM GATEWAY] to %s: %s%n", recipient, message);
21    }
22}
23 
24public class PolymorphismDemo {
25    public static void main(String[] args) {
26        // Upcasting: Superclass reference pointing to subclass objects!
27        List<NotificationService> services = new ArrayList<>();
28        services.add(new EmailNotification());
29        services.add(new SmsNotification());
30 
31        // Polymorphic invocation: Resolved dynamically at runtime!
32        for (NotificationService service : services) {
33            service.send("student@mskinstitute.in", "Batch starts Monday 9:00 AM");
34        }
35    }
36}

⚠️ Overriding Rules:

1
Method signature (name, parameters, return type or covariant type) must match.
2
Visibility cannot be reduced (e.g., cannot override a public method as private).
3
Private and static methods cannot be overridden.

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The final Keyword: Final Variables, Methods, and Classes

Method Overriding and Dynamic Method Dispatch (Runtime Polymorphism)

Intermediate14 min read•Updated: 2026-10-22

Study Materials

🎪 Method Overriding and Dynamic Method Dispatch

Introduction

💻 Upcasting & Dynamic Dispatch in Action

1import java.util.List;
2import java.util.ArrayList;
3 
4class NotificationService {
5    public void send(String recipient, String message) {
6        System.out.printf("[DEFAULT NOTIFICATION] to %s: %s%n", recipient, message);
7    }
8}
9 
10class EmailNotification extends NotificationService {
11    @Override
12    public void send(String recipient, String message) {
13        System.out.printf("[EMAIL DISPATCHED] to %s: %s%n", recipient, message);
14    }
15}
16 
17class SmsNotification extends NotificationService {
18    @Override
19    public void send(String recipient, String message) {
20        System.out.printf("[SMS DISPATCHED via TELECOM GATEWAY] to %s: %s%n", recipient, message);
21    }
22}
23 
24public class PolymorphismDemo {
25    public static void main(String[] args) {
26        // Upcasting: Superclass reference pointing to subclass objects!
27        List<NotificationService> services = new ArrayList<>();
28        services.add(new EmailNotification());
29        services.add(new SmsNotification());
30 
31        // Polymorphic invocation: Resolved dynamically at runtime!
32        for (NotificationService service : services) {
33            service.send("student@mskinstitute.in", "Batch starts Monday 9:00 AM");
34        }
35    }
36}

⚠️ Overriding Rules:

1
Method signature (name, parameters, return type or covariant type) must match.
2
Visibility cannot be reduced (e.g., cannot override a public method as private).
3
Private and static methods cannot be overridden.

Next Lesson

The final Keyword: Final Variables, Methods, and Classes

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Inheritance with extends and the super Keyword	The final Keyword: Final Variables, Methods, and Classes

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next