Tag: Are Java annotations useful?

Annotations are used to provide supplemental information about a program . Annotations start with ‘@’. Annotations do not change the action of a compiled program. Annotations help to associate metadata (information) to the program elements i.e. instance variables, constructors, methods, classes, etc.

@interface is used to create your own (custom) Java annotations . Annotations are defined in their own file, just like a Java class or interface. Here is custom Java annotation example: @interface MyAnnotation { String value(); String name(); int age(); String[] newNames(); }

An informative annotation type used to indicate that an interface type declaration is intended to be a functional interface as defined by the Java Language Specification . Indicates that a method declaration is intended to override a method declaration in a supertype.

In C#, attributes are classes that inherit from the Attribute base class . Any class that inherits from Attribute can be used as a sort of “tag” on other pieces of code. For instance, there is an attribute called ObsoleteAttribute . This is used to signal that code is obsolete and shouldn’t be used anymore.

These annotations generate or suppress compiler warnings and errors. Applying them consistently is often a good practice since adding them can prevent future programmer error .