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What does annotation mean in java

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Release： 2024-05-01 18:27:33

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Java annotations are metadata that provide information about code elements, including: Record Documentation Configuration Validation Generated Code

What does annotation mean in java

## Annotations in Java

In Java, annotations are a type of metadata that can be used to provide additional information about a class, method, field, or package. They are used to:

Documentation: Provide information about the intent and purpose of the code.
Configuration: Configure the behavior of a framework or tool, such as Spring or Hibernate.
Verification: Verify that the code complies with certain rules.
Generate code: Generate automatically generated code, such as persistence mapping for JPA entities.

How to use annotations

To use annotations, you need to use the

@ symbol followed by the name of the annotation class where required. For example:

<code class="java">@Override
public String toString() {
    return super.toString();
}</code>

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This example uses the

@Override annotation to indicate that the toString() method is intended to override a method of the same name in the superclass.

Type annotations

There are four types of annotations in Java:

Class annotations: Applicable to class or interface.
Method annotations: Applies to methods.
Field annotations: Applies to fields.
Package annotations: Applies to packages.

Common annotations

Some common Java annotations include:

@Override: Instructions Methods override methods in superclasses.
@Deprecated: Warns developers that this method is deprecated and should be avoided.
@SuppressWarnings: Suppress compiler warnings.
@Autowired: Used in Spring to autowire beans.
@Entity: Used in JPA to map classes to database tables.

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