Type Annotations

The Java 6 annotation syntax is useful but limited. The Type Annotations project is implementing a Java language extension that permits annotations to be written on uses of types. One example of the new syntax is generic type arguments, as in List<@NonNull Object>. The type annotation syntax is also known as "JSR 308".

This Project is sponsored by the OpenJDK Compiler Group and is targeted for inclusion in the Java SE 7 Platform.

Specification

The Type Annotations specification indicates changes to the Java language and platform.

PDF
HTML

Implementation

Download (includes source, platform-independent binary, and documentation)
Documentation (included in the distribution; includes installation instructions)
Changelog
Mercurial repository

Other tools that use type annotations

Several other tools already use the type annotation syntax.

The Checker Framework makes it easy to write and use compiler plug-ins that implement a custom type system. The compiler plug-in enables a programmer to find bugs or to verify their absence. The Checker Framework comes with several type-checking plug-ins that you can try right away.
Inference tools automatically add annotations to your code, making it even easier to start using the checkers distributed with the Checker Framework.
- Daikon infers the @Nullable type qualifier.
- JastAdd infers the @NonNull type qualifier.
- Javarifier infers the @ReadOnly type qualifier.
Annotation file utilities extract annotations from, and write annotations to, .java and .class files.

Community

Awards

Received the Most Innovative Java SE/EE JSR of the Year award in 2007.
Nominated for the Most Outstanding Spec Lead for Java SE/EE award in 2008.