Using Java Bean Validation for Method Parameters and Return Values (JNNC Technologies)

Java’s static type system is a robust mechanism that lets you specify a method’s preconditions and postconditions (from the caller’s perspective: what to supply and what to expect) with the compiler assuring that these conditions are fulfilled at run time. Java Bean Validation takes this constrain model further and closer to a specific domain. It provides a fully-fledged validation API, which not only allows to validate the fields of a class through a set of intuitive validation constraints. As we will see in this post, it also gives developers the ability to reuse these constraints in arguments and return values in both regular methods and constructors and validate them in a design-by-contract fashion – either manually or automatically via Java EE interceptors.