# 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

```bash
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/