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Serial
public
abstract
@interface
Serial
implements
Annotation
Indicates that an annotated field or method is part of the serialization mechanism defined by the
Java Object Serialization Specification. This
annotation type is intended to allow compile-time checking of
serialization-related declarations, analogous to the checking
enabled by the Override annotation type to
validate method overriding. Serializable classes are encouraged to
use @Serial annotations to help a compiler catch
mis-declared serialization-related fields and methods,
mis-declarations that may otherwise be difficult to detect.
Specifically, annotations of this type should be
applied to serialization-related methods and fields in classes
declared to be Serializable. The five serialization-related
methods are:
private void writeObject(java.io.ObjectOutputStream stream) throws IOException
private void readObject(java.io.ObjectInputStream stream) throws IOException, ClassNotFoundException
private void readObjectNoData() throws ObjectStreamException
- ANY-ACCESS-MODIFIER
Object writeReplace() throws ObjectStreamException
- ANY-ACCESS-MODIFIER
Object readResolve() throws ObjectStreamException
The two serialization-related fields are:
private static final ObjectStreamField[] serialPersistentFields
private static final long serialVersionUID
Compilers are encouraged to validate that a method or field marked with a
@Serial annotation is one of the defined serialization-related
methods or fields declared in a meaningful context and issue a warning
if that is not the case.
It is a semantic error to apply this annotation to other fields or methods, including:
- fields or methods in a class that is not
Serializable
- fields or methods of the proper structural declaration, but in
a type where they are ineffectual. For example,
enum types
are defined to have a serialVersionUID of 0L so a
serialVersionUID field declared in an enum type is
ignored. The five serialization-related methods identified above
are likewise ignored for an enum type.
- in a class that is
Externalizable:
- method declarations of
writeObject, readObject, and readObjectNoData
- a field declaration for
serialPersistentFields
While the Externalizable interface extends Serializable, the three methods and one field above are
not used for externalizable classes.
Note that serialization mechanism accesses its designated fields
and methods reflectively and those fields and methods may appear
otherwise unused in a
Serializable class.
Summary
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2025-02-10 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-02-10 UTC."],[],[],null,["# Serial\n\nAdded in [API level 34](/guide/topics/manifest/uses-sdk-element#ApiLevels) \nSummary: [Inherited Methods](#inhmethods) \n\nSerial\n======\n\n\n`\npublic\n\n\nabstract\n@interface\nSerial\n`\n\n\n`\n\n\nimplements\n\n`[Annotation](/reference/java/lang/annotation/Annotation)`\n\n\n`\n\n|----------------|\n| java.io.Serial |\n\n\u003cbr /\u003e\n\n*** ** * ** ***\n\nIndicates that an annotated field or method is part of the [serialization mechanism](/reference/java/io/Serializable) defined by the\nJava Object Serialization Specification. This\nannotation type is intended to allow compile-time checking of\nserialization-related declarations, analogous to the checking\nenabled by the [Override](/reference/java/lang/Override) annotation type to\nvalidate method overriding. `Serializable` classes are encouraged to\nuse `@Serial` annotations to help a compiler catch\nmis-declared serialization-related fields and methods,\nmis-declarations that may otherwise be difficult to detect.\n\nSpecifically, annotations of this type should be\napplied to serialization-related methods and fields in classes\ndeclared to be `Serializable`. The five serialization-related\nmethods are:\n\n- `private void writeObject(java.io.ObjectOutputStream stream) throws IOException`\n- `private void readObject(java.io.ObjectInputStream stream) throws IOException, ClassNotFoundException`\n- `private void readObjectNoData() throws ObjectStreamException`\n- *ANY-ACCESS-MODIFIER* `Object writeReplace() throws ObjectStreamException`\n- *ANY-ACCESS-MODIFIER* `Object readResolve() throws ObjectStreamException`\n\nThe two serialization-related fields are:\n\n\u003c!-- --\u003e\n\n- `private static final ObjectStreamField[] serialPersistentFields`\n- `private static final long serialVersionUID`\n\nCompilers are encouraged to validate that a method or field marked with a `@Serial` annotation is one of the defined serialization-related methods or fields declared in a meaningful context and issue a warning if that is not the case.\n\nIt is a semantic error to apply this annotation to other fields or methods, including:\n\n- fields or methods in a class that is not `Serializable`\n- fields or methods of the proper structural declaration, but in a type where they are ineffectual. For example, `enum` types are defined to have a `serialVersionUID` of `0L` so a `serialVersionUID` field declared in an `enum` type is ignored. The five serialization-related methods identified above are likewise ignored for an `enum` type.\n- in a class that is `Externalizable`:\n - method declarations of `writeObject`, `readObject`, and `readObjectNoData`\n - a field declaration for `serialPersistentFields`\n\n While the `Externalizable` interface extends `Serializable`, the three methods and one field above are *not* used for externalizable classes.\n\nNote that serialization mechanism accesses its designated fields and methods reflectively and those fields and methods may appear otherwise unused in a `Serializable` class.\n\n\u003cbr /\u003e\n\n**See also:**\n\n- [Serializable](/reference/java/io/Serializable)\n- [Externalizable](/reference/java/io/Externalizable)\n\nSummary\n-------\n\n| ### Inherited methods |\n|-----------------------|---|\n| From interface ` `[java.lang.annotation.Annotation](/reference/java/lang/annotation/Annotation)` ` |-------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` abstract `[Class](/reference/java/lang/Class)`\u003c? extends `[Annotation](/reference/java/lang/annotation/Annotation)`\u003e` | ` `[annotationType](/reference/java/lang/annotation/Annotation#annotationType())`() ` Returns the annotation interface of this annotation. | | ` abstract boolean` | ` `[equals](/reference/java/lang/annotation/Annotation#equals(java.lang.Object))`(`[Object](/reference/java/lang/Object)` obj) ` Returns true if the specified object represents an annotation that is logically equivalent to this one. | | ` abstract int` | ` `[hashCode](/reference/java/lang/annotation/Annotation#hashCode())`() ` Returns the hash code of this annotation. | | ` abstract `[String](/reference/java/lang/String) | ` `[toString](/reference/java/lang/annotation/Annotation#toString())`() ` Returns a string representation of this annotation. | ||"]]
