code: /*
   * 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 tools.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.
   *
   * <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 {@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;
  }
  