Java annotation: Difference between revisions

Revision as of 14:41, 13 August 2025

Latest revision as of 07:59, 17 August 2025

(5 intermediate revisions by one other user not shown)

Line 42:

| <code>@FunctionalInterface</code> || <code>java.lang</code> || Marks an interface as intended to be a functional interface.

|-

| <code>@Override</code> || <code>java.lang</code> || ChecksMarks that the method is an [[Method overriding|overrideoverrides]] an ancestor class-defined method. Causes a [[compilation error]] if the method is not found in one of the [[parent class]]es or implemented [[Interface (Java)|interfaces]].

|-

| <code>@SafeVarargs</code> || <code>java.lang</code> || Suppress warnings for all callers of a method or constructor with a [[Generics in Java|generics]] [[Variadic function|varargs]] parameter, since Java 7.

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In [[Jakarta EE]] (formerly Java Platform, Enterprise Edition), the following annotations also exist in <code>jakarta.annotation</code> (formerly <code>javax.annotation</code>):<ref>{{cite web

| title = Jakarta Annotations API 1.3.5 API

| url = https://jakartaee.github.io/common-annotations-api/apidocs/

| publisher = [[Jakarta EE]]

| access-date = 2025-08-13

}}</ref><ref>{{cite web

| title = Jakarta Annotations

| url = https://jakarta.ee/specifications/annotations/3.0/annotations-spec-3.0.html

| publisher = [[Jakarta EE]]

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<syntaxhighlight lang=Java>

package com.acme.proj.annotation;

import java.lang.annotation.Documented;

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@Documented

@Retention(RetentionPolicy.RUNTIME)

@Target({
ElementType.TYPE, ElementType.METHOD,

ElementType.CONSTRUCTOR, ElementType.ANNOTATION_TYPE,

ElementType.PACKAGE, ElementType.FIELD, ElementType.LOCAL_VARIABLE
})

@Inherited

public @interface Unfinished {

public enum Priority { LOW, MEDIUM, HIGH }

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<syntaxhighlight lang=Java>

package com.acme.proj.annotation;

public @interface UnderConstruction {

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<syntaxhighlight lang=Java>

package com.acme.proj.validators;

import javax.faces.application.FacesMessage;

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import javax.faces.validator.ValidatorException;

import com.acme.proj.annotation.UnderConstruction;

import com.acme.proj.annotation.Unfinished;

import com.acme.proj.annotation.Unfinished.Priority;

import com.acme.proj.util.Util;

@UnderConstruction(owner = "Jon Doe")

public class DateValidator implements Validator {

public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {

throws ValidatorException {

String date = (String) value;

String errorLabel = "Please enter a valid date.";

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if (!Util.validateAGivenDate(date)) {

@Unfinished(
changedBy = "Steve",

value = "whether to add message to context or not, confirm",

priority = Priority.HIGH

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<syntaxhighlight lang=Java>

// This is the annotation being applied to a class

@TypeHeader(
developer = "Bob Bee",

lastModified = "2013-02-12",

teamMembers = { "Ann", "Dan", "Fran" },

meaningOfLife = 42
)

public class SetCustomAnnotation {

// Class contents go here