Slides associated with the EclipseCon session: https://www.eclipsecon.org/france2014/session/handle-billion-dollar-mistake-java-help-tools-understand-your-code Note: the session was essentially code-based, so the slides may not be really useful taken alone.

1. Handle The Billion-Dollar
Mistake In Java
Help tools understand your code
Baptiste Mathus – MiPih
EclipseCon France 2014

2. Baptiste Mathus - EclipseCon France 2014 - @bmathus
http://batmat.net

3. Agenda
•Null – a billion-dollar mistake?
•@Nonnull, @Nullable… @WTF?
•Tooling
•Alternatives
Baptiste Mathus - EclipseCon France 2014 - @bmathus

4. The null concept: a billion-dollar mistake?
His creator, Sir Charles Antony Richard Hoare, says yes! :-)
[...] languages designs is serious scientific
engineering activity. And we should begin to
take responsibility for the mistakes our
users make in the use of our languages.
– Tony Hoare
Baptiste Mathus - EclipseCon France 2014 - @bmathus

5. Baptiste Mathus - EclipseCon France 2014 - @bmathus
Unexpected…

6. JSR305 : Annotations for software detections
Why @Nonnull… annotations?
« they express design decisions that may be implicit, or described in
documentation, but not easily available to tools »
Baptiste Mathus - EclipseCon France 2014 - @bmathus

7. Code talks, slides walks…
Baptiste Mathus - EclipseCon France 2014 - @bmathus

8. References
• Null References: The Billion Dollar Mistake
• http://www.infoq.com/presentations/Null-References-The-Billion-Dollar-Mistake-
Tony-Hoare
• Eclipse Help For Using Null Analysis
• http://eclip.se/2f
• JSR 308: Annotations on Java Types
• https://www.jcp.org/en/jsr/detail?id=308
• To go further: the Checker Framework
• http://types.cs.washington.edu/checker-framework/
• Experiment: runtime report of non-compliant calls (WIP)
• https://github.com/Batmat/jsr305reporter
Baptiste Mathus - EclipseCon France 2014 - @bmathus