Factory Method Design Pattern — Java Example
Pattern: Creational → Factory Method Article: https://ankurm.com/factory-method-design-pattern-java/
What this example shows
A notification system where the "send" logic decides which channel object to create, instead of the client doing it with a switch statement. Notification is the product interface; EmailNotification, SmsNotification, and PushNotification are concrete products. NotificationSender declares the factory method and a template send() step shared by every channel; EmailSender, SmsSender, and PushSender each override the factory method to produce their own notification type. NotificationService is shown separately as the anti-pattern this pattern replaces — it is not called by Main. Main demonstrates the cost of adding a new channel (Slack) by adding one new product and one new creator, with zero changes to existing classes.
How to run
javac factory-method/*.java -d out/factory-method
java -cp out/factory-method factorymethod.Main
Requires Java 25.
Post Section ↔ File Mapping
| Post Section | File(s) |
|---|---|
| The Problem: Object Creation Leaks Into Business Logic | NotificationService.java (anti-pattern shown for contrast — not called by Main) |
| Part 1 — The Notification Interface | Notification.java |
| Part 2 — The Concrete Notification Classes | EmailNotification.java, SmsNotification.java, PushNotification.java |
| Part 3 — The NotificationSender Class | NotificationSender.java |
| Part 4 — The Concrete Sender Subclasses | EmailSender.java, SmsSender.java, PushSender.java |
| Part 5 — Running It: Client Code and Output | Main.java |
| Adding a New Channel (Slack) | SlackNotification.java, SlackSender.java |
Article: https://ankurm.com/factory-method-design-pattern-java/ All patterns: https://ankurm.com/design-patterns-java/