Serial

public abstract @interface Serial
implements Annotation

java.io.Serial

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.

See also:

Serializable
Externalizable

Summary

Inherited methods

From interface


        
          java.lang.annotation.Annotation

`abstract Class<? extends Annotation>`	`annotationType()` Returns the annotation interface of this annotation.
`abstract boolean`	`equals(Object obj)` Returns true if the specified object represents an annotation that is logically equivalent to this one.
`abstract int`	`hashCode()` Returns the hash code of this annotation.
`abstract String`	`toString()` Returns a string representation of this annotation.