Java annotation

Java annotations

A java annotation in any language is a form of syntactic metadata that can be added to the java source code.

There are following types of annotations in Java - 

Annotations applied to Java code:

• @Override - Checks that the method is an override. Causes a compile error if the method is not found in one of the parent classes or implemented interfaces.
• @Deprecated - Marks the method as obsolete. Causes a compile warning if the method is used.
• @SuppressWarnings - Instructs the compiler to suppress the compile time warnings specified in the annotation parameters.
• @SafeVarargs - Suppress warnings for all callers of a method or constructor with a generics varargs parameter, since Java 7.
• @FunctionalInterface - Specifies that the type declaration is intended to be a functional interface, since Java 8.

Annotations applied to other annotations:

• @Retention - Specifies how the marked annotation is stored—Whether in code only, compiled into the class, or available at runtime through reflection.
• @Documented - Marks another annotation for inclusion in the documentation.
• @Target - Marks another annotation to restrict what kind of Java elements the annotation may be applied to.
• @Inherited - Marks another annotation to be inherited to subclasses of annotated class (by default annotations are not inherited to subclasses).
• @Repeatable - Specifies that the annotation can be applied more than once to the same declaration.