package com.google.gson.annotations;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* An annotation that indicates this member should be exposed for JSON serialization or
* deserialization.
*
* <p>
* This annotation has no effect unless you build {@link com.google.gson.Gson} with a
* {@link com.google.gson.GsonBuilder} and invoke
* {@link com.google.gson.GsonBuilder#excludeFieldsWithoutExposeAnnotation()} method.
* </p>
*
* <p>
* Here is an example of how this annotation is meant to be used:
* <p>
*
* <pre>
* public class User {
* @Expose private String firstName;
* @Expose(serialize = false) private String lastName;
* @Expose (serialize = false, deserialize = false) private String emailAddress;
* private String password;
* }
* </pre>
* </p>
* If you created Gson with {@code new Gson()}, the {@code toJson()} and {@code fromJson()} methods
* will use the {@code password} field along-with {@code firstName}, {@code lastName}, and
* {@code emailAddress} for serialization and deserialization. However, if you created Gson with
* {@code Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create()} then the
* {@code toJson()} and {@code fromJson()} methods of Gson will exclude the {@code password} field.
* This is because the {@code password} field is not marked with the {@code @Expose} annotation.
* Gson will also exclude {@code lastName} and {@code emailAddress} from serialization since
* {@code serialize} is set to {@code false}. Similarly, Gson will exclude {@code emailAddress} from
* deserialization since {@code deserialize} is set to false.
*
* <p>
* Note that another way to achieve the same effect would have been to just mark the
* {@code password} field as {@code transient}, and Gson would have excluded it even with default
* settings. The {@code @Expose} annotation is useful in a style of programming where you want to
* explicitly specify all fields that should get considered for serialization or deserialization.
*
* @author Inderjeet Singh
* @author Joel Leitch
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Expose {
/**
* If {@code true}, the field marked with this annotation is written out in the JSON while
* serializing. If {@code false}, the field marked with this annotation is skipped from the
* serialized output. Defaults to {@code true}.
*
* @since 1.4
*/
public boolean serialize() default true;
/**
* If {@code true}, the field marked with this annotation is deserialized from the JSON. If
* {@code false}, the field marked with this annotation is skipped during deserialization.
* Defaults to {@code true}.
*
* @since 1.4
*/
public boolean deserialize() default true;
}