1.4 KiB
Mediator Design Pattern — Java Example
Pattern: Behavioral → Mediator Article: https://ankurm.com/mediator-design-pattern-java/
What this example shows
A chat room where users never talk to each other directly. ChatMediator declares the hub contract (sendMessage()/addUser()). User is a colleague — it knows only the mediator, never other users. ChatRoom is the concrete mediator: it holds the list of users and routes every message to everyone except the sender. Main adds three users and has each one broadcast a message, then prints the O(N) vs O(N²) connection-count comparison.
How to run
javac mediator/*.java -d out/mediator
java -cp out/mediator mediator.Main
Requires Java 25.
Post Section ↔ File Mapping
| Post Section | File(s) |
|---|---|
| Implementation: Chat Room — the Mediator interface | ChatMediator.java |
| Implementation: Chat Room — the Colleague | User.java |
| Implementation: Chat Room — the Concrete Mediator | ChatRoom.java |
| Implementation: Chat Room — wiring it together | Main.java |
Note: the "Mediator in Practice: MVC and Spring Events" snippet (ApplicationEventPublisher/@EventListener example) is illustrative only — it is not part of this repository's runnable example.
Article: https://ankurm.com/mediator-design-pattern-java/ All patterns: https://ankurm.com/design-patterns-java/