#Java annotations on parameters how to#
#Java annotations on parameters code#

This annotation will cause the compiler to generate a warning when the marked element is found in source code. Most often, another element has been created that encapsulates the marked element’s functionality, and the marked element will no longer be supported. Indicates that the marked element should no longer be used.

#Java annotations on parameters code#

NEED INFO? Annotations have no direct effect on code operation, but at processing time, they can cause an annotation processor to generate files or provide informational messages. Annotations have no direct effect on code operation, but at processing time, they can cause an annotation processor to generate files or provide informational messages. Overview of Built-in AnnotationsĪnnotations can be easily recognized in code because the annotation name is prefaced with the character. After reading this article, you’ll be able to use type annotations to enforce stronger typing in your Java source code.

#Java annotations on parameters how to#

This article begins with a brief overview of annotations, and then you’ll learn how to apply annotations to Java types, write type annotations, and use compile-time plug-ins for type checking. Type-checking frameworks comprise type annotation definitions and one or more pluggable modules that are used with the compiler for annotation processing. There are also a number of type-checking frameworks that can be downloaded, which can be used as plug-ins to the Java compiler to check and enforce types that have been annotated. Java SE 8 does not provide a default type-checking framework, but it is possible to write custom annotations and processors for type checking. Compiler checkers can be written to verify annotated code, enforcing rules by generating compiler warnings when code does not meet certain requirements. This allows developers to apply the benefits of annotations in even more places.Īnnotations on types can be useful in many cases, most notably to enforce stronger typing, which can help reduce the number of errors within code. This means annotations can now be applied anywhere a type is specified, including during class instance creation, type casting, the implementation of interfaces, and the specification of throws clauses. Beginning in Java SE 8, annotations can be applied to types in addition to all of their existing uses within Java declarations. This JSR builds upon the existing annotation framework, allowing type annotations to become part of the language. JSR 308, Annotations on Java Types, has been incorporated as part of Java SE 8. Originally published in the March/April 2014 issue of Java Magazine.