# Template Method Design Pattern — Java Example

**Pattern:** Behavioral → Template Method
**Article:** https://ankurm.com/template-method-design-pattern-java/

## What this example shows

A data migration pipeline with a fixed skeleton and variable steps. `DataMigration` declares `migrate()` as `final` — the sequence (connect, validate, read, transform, write, notify, disconnect) can never be reordered or skipped by a subclass. `getSourceName()`, `connect()`, `readData()`, and `transformData()` are abstract steps each subclass must supply; `validate()`, `writeData()`, and `disconnect()` are concrete steps shared by everyone; `sendNotification()` is a hook with a default of `true` that a subclass can override. `CsvMigration` uses every default unchanged. `ApiMigration` overrides the hook to stay silent. `Main` runs both through the identical skeleton.

## How to run

```bash
javac template-method/*.java -d out/template-method
java -cp out/template-method template.Main
```

Requires Java 25.

## Post Section ↔ File Mapping

| Post Section | File(s) |
|---|---|
| Implementation: Data Migration Pipeline — the abstract class & template method | `DataMigration.java` |
| Implementation: Data Migration Pipeline — CsvMigration | `CsvMigration.java` |
| Implementation: Data Migration Pipeline — ApiMigration | `ApiMigration.java` |
| Implementation: Data Migration Pipeline — wiring it together | `Main.java` |

Article: https://ankurm.com/template-method-design-pattern-java/
All patterns: https://ankurm.com/design-patterns-java/