The good API design

I’ve stumbled upon a nice checklist wrapping up API design guidelines. An extract:

1. Favor placing API and implementation into separate packages
2. Favor placing APIs into high-level packages and implementation into lower-level packages
3. Consider breaking up large APIs into several packages
4. Consider putting API and implementation packages into separate Java archives
5. Avoid (minimize) internal dependencies on implementation classes in APIs
6. Avoid unnecessary API fragmentation
7. Do not place public implementation classes in the API package
8. Do not create dependencies between callers and implementation classes
9. Do not place unrelated APIs into the same package
10. Do not place API and SPI into the same package
11. Do not move or rename the package of an already released public API

See the full checklist here:

http://theamiableapi.com/2012/01/16/java-api-design-checklist/