Home > Articles > Programming > Java

  • Print
  • + Share This
This chapter is from the book

10.5. Standard Annotations

Java SE defines a number of annotation interfaces in the java.lang, java.lang.annotation, and javax.annotation packages. Four of them are meta-annotations that describe the behavior of annotation interfaces. The others are regular annotations that you can use to annotate items in your source code. Table 10.2 shows these annotations. We’ll discuss them in detail in the following two sections.

Table 10.2. The Standard Annotations

Annotation Interface

Applicable To




Marks item as deprecated.


All but packages and annotations

Suppresses warnings of the given type.



Checks that this method overrides a superclass method.

PostConstruct PreDestroy


The marked method should be invoked immediately after construction or before removal.


Classes, interfaces, methods, fields

On a class or interface, marks it as a resource to be used elsewhere. On a method or field, marks it for “injection.”


Classes, interfaces

Specifies an array of resources.



Marks an item as source code that has been generated by a tool.



Specifies the items to which this annotation can be applied.



Specifies how long this annotation is retained.



Specifies that this annotation should be included in the documentation of annotated items.



Specifies that this annotation, when applied to a class, is automatically inherited by its subclasses.

10.5.1. Annotations for Compilation

The @Deprecated annotation can be attached to any items for which use is no longer encouraged. The compiler will warn when you use a deprecated item. This annotation has the same role as the @deprecated Javadoc tag.

The @SuppressWarnings annotation tells the compiler to suppress warnings of a particular type, for example,


The @Override annotation applies only to methods. The compiler checks that a method with this annotation really overrides a method from the superclass. For example, if you declare

public MyClass
   @Override public boolean equals(MyClass other);
   . . .

then the compiler will report an error. After all, the equals method does not over-ride the equals method of the Object class because that method has a parameter of type Object, not MyClass.

The @Generated annotation is intended for use by code generator tools. Any generated source code can be annotated to differentiate it from programmer-provided code. For example, a code editor can hide the generated code, or a code generator can remove older versions of generated code. Each annotation must contain a unique identifier for the code generator. A date string (in ISO 8601 format) and a comment string are optional. For example,

@Generated("com.horstmann.beanproperty", "2008-01-04T12:08:56.235-0700");

10.5.2. Annotations for Managing Resources

The @PostConstruct and @PreDestroy annotations are used in environments that control the lifecycle of objects, such as web containers and application servers. Methods tagged with these annotations should be invoked immediately after an object has been constructed or immediately before it is being removed.

The @Resource annotation is intended for resource injection. For example, consider a web application that accesses a database. Of course, the database access information should not be hardwired into the web application. Instead, the web container has some user interface for setting connection parameters and a JNDI name for a data source. In the web application, you can reference the data source like this:

private DataSource source;

When an object containing this field is constructed, the container “injects” a reference to the data source.

10.5.3. Meta-Annotations

The @Target meta-annotation is applied to an annotation, restricting the items to which the annotation applies. For example,

@Target({ElementType.TYPE, ElementType.METHOD})
public @interface BugReport

Table 10.3 shows all possible values. They belong to the enumerated type ElementType. You can specify any number of element types, enclosed in braces.

Table 10.3. Element Types for the @Target Annotation

Element Type

Annotation Applies To


Annotation type declarations




Classes (including enum) and interfaces (including annotation types)






Fields (including enum constants)


Method or constructor parameters


Local variables

An annotation without an @Target restriction can be applied to any item. The compiler checks that you apply an annotation only to a permitted item. For example, if you apply @BugReport to a field, a compile-time error results.

The @Retention meta-annotation specifies how long an annotation is retained. You can specify at most one of the values in Table 10.4. The default is RetentionPolicy.CLASS.

Table 10.4. Retention Policies for the @Retention Annotation

Retention Policy



Annotations are not included in class files.


Annotations are included in class files, but the virtual machine need not load them.


Annotations are included in class files and loaded by the virtual machine. They are available through the reflection API.

In Listing 10.11 on p. 925, the @ActionListenerFor annotation was declared with RetentionPolicy.RUNTIME because we used reflection to process annotations. In the following two sections, you will see examples of processing annotations at the source and class file levels.

The @Documented meta-annotation gives a hint to documentation tools such as Javadoc. Documented annotations should be treated just like other modifiers such as protected or static for documentation purposes. The use of other annotations is not included in the documentation. For example, suppose we declare @ActionListenerFor as a documented annotation:

public @interface ActionListenerFor

Now the documentation of each annotated method contains the annotation, as shown in Figure 10.2.

Figure 10.2

Figure 10.2. Documented annotations

If an annotation is transient (such as @BugReport), you should probably not document its use.

The @Inherited meta-annotation applies only to annotations for classes. When a class has an inherited annotation, then all of its subclasses automatically have the same annotation. This makes it easy to create annotations that work as marker interfaces, such as Serializable.

In fact, an annotation @Serializable would be more appropriate than the Serializable marker interface with no methods. A class is serializable because there is runtime support for reading and writing its fields, not because of any principles of object-oriented design. An annotation describes this fact better than does interface inheritance. Of course, the Serializable interface was created in JDK 1.1, long before annotations existed.

Suppose you define an inherited annotation @Persistent to indicate that objects of a class can be saved in a database. Then the subclasses of persistent classes are automatically annotated as persistent.

@Inherited @interface Persistent { }
@Persistent class Employee { . . . }
class Manager extends Employee { . . . } // also @Persistent

When the persistence mechanism searches for objects to store in the database, it will detect both Employee and Manager objects.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020