Google has a open source library called contracts for java.
Contracts for Java is our new open source tool. Preconditions,
postconditions, and invariants are added as Java boolean expressions
inside annotations. By default these do nothing, but enabled via a JVM
argument, they’re checked at runtime.
• @Requires, @Ensures, @ThrowEnsures and @Invariant specify contracts as Java boolean expressions
• Contracts are inherited from both interfaces and classes and can be selectively enabled at runtime
contracts for java.
