Annotations
Annotations provide metadata about program elements such as classes, interfaces, methods, fields, parameters, and constructors.
They do not change program logic directly, but they supply information to the compiler, build tools, or runtime frameworks.
Some built-in annotations are used directly in source code to help the compiler detect errors, suppress warnings, or enforce constraints.
Common Built-in Annotations (Applied to Code)
@Override
Indicates that a method is intended to override a method from a superclass or interface. The compiler will generate an error if the method does not correctly override a parent method.
@Deprecated
Marks a program element as deprecated, meaning it should no longer be used. The compiler will generate a warning when deprecated elements are used.
@FunctionalInterface
Indicates that an interface is intended to be a functional interface, i.e., it must contain exactly one abstract method. This enables use with lambda expressions and causes a compile-time error if the rule is violated.
@SuppressWarnings
Instructs the compiler to suppress specified warnings that would otherwise be generated. Common values include "unchecked", "deprecation", and "rawtypes".
@SafeVarargs
When applied to a method or constructor, it asserts that the method does not perform unsafe operations on its varargs parameter involving generics. It suppresses unchecked warnings related to heap pollution.