Contracts for java is a contract programming framework for java, which uses annotation processing and bytecode instrumentation to provide run-time checking.

contracts for java enables you to annotate your code with contracts in the form of preconditions, postconditions and invariants.

these contract annotations are:
- easy to write and read
- checked at runtime
annotating code with contracts helps you:
* design,
* document,
* test, and
* debug
programs.