/*
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.gson.annotations;

import java.lang.annotation.Documented;
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.
This annotation has no effect unless you build Gson with a GsonBuilder and invoke GsonBuilder.excludeFieldsWithoutExposeAnnotation() method.
Here is an example of how this annotation is meant to be used:
public class User {
  @Expose private String firstName;
  @Expose(serialize = false) private String lastName;
  @Expose (serialize = false, deserialize = false) private String emailAddress;
  private String password;
}
 If you created Gson with new Gson(), the toJson() and fromJson() methods will use the password field along-with firstName, lastName, and emailAddress for serialization and deserialization. However, if you created Gson with Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create() then the toJson() and fromJson() methods of Gson will exclude the password field. This is because the password field is not marked with the @Expose annotation. Gson will also exclude lastName and emailAddress from serialization since serialize is set to false. Similarly, Gson will exclude emailAddress from deserialization since deserialize is set to false. 
Note that another way to achieve the same effect would have been to just mark the password field as transient, and Gson would have excluded it even with default settings. The @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, Joel Leitch/**
 * 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 {
 *   &#64Expose private String firstName;
 *   &#64Expose(serialize = false) private String lastName;
 *   &#64Expose (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
 */
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Expose {
  
  
If true, the field marked with this annotation is written out in the JSON while serializing. If false, the field marked with this annotation is skipped from the serialized output. Defaults to true. 
Since:
1.4/**
   * 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 true, the field marked with this annotation is deserialized from the JSON. If false, the field marked with this annotation is skipped during deserialization. Defaults to true. 
Since:
1.4/**
   * 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;
}