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+/*
+ * Copyright (C) 2014 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 com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * An annotation that indicates the Gson {@link TypeAdapter} to use with a class
+ * or field.
+ *
+ * <p>Here is an example of how this annotation is used:</p>
+ * <pre>
+ * &#64JsonAdapter(UserJsonAdapter.class)
+ * public class User {
+ *   public final String firstName, lastName;
+ *   private User(String firstName, String lastName) {
+ *     this.firstName = firstName;
+ *     this.lastName = lastName;
+ *   }
+ * }
+ * public class UserJsonAdapter extends TypeAdapter&lt;User&gt; {
+ *   &#64Override public void write(JsonWriter out, User user) throws IOException {
+ *     // implement write: combine firstName and lastName into name
+ *     out.beginObject();
+ *     out.name("name");
+ *     out.value(user.firstName + " " + user.lastName);
+ *     out.endObject();
+ *     // implement the write method
+ *   }
+ *   &#64Override public User read(JsonReader in) throws IOException {
+ *     // implement read: split name into firstName and lastName
+ *     in.beginObject();
+ *     in.nextName();
+ *     String[] nameParts = in.nextString().split(" ");
+ *     in.endObject();
+ *     return new User(nameParts[0], nameParts[1]);
+ *   }
+ * }
+ * </pre>
+ *
+ * Since User class specified UserJsonAdapter.class in &#64JsonAdapter annotation, it
+ * will automatically be invoked to serialize/deserialize User instances. <br>
+ *
+ * <p> Here is an example of how to apply this annotation to a field.
+ * <pre>
+ * private static final class Gadget {
+ *   &#64JsonAdapter(UserJsonAdapter2.class)
+ *   final User user;
+ *   Gadget(User user) {
+ *     this.user = user;
+ *   }
+ * }
+ * </pre>
+ *
+ * It's possible to specify different type adapters on a field, that
+ * field's type, and in the {@link com.google.gson.GsonBuilder}. Field
+ * annotations take precedence over {@code GsonBuilder}-registered type
+ * adapters, which in turn take precedence over annotated types.
+ *
+ * <p>The class referenced by this annotation must be either a {@link
+ * TypeAdapter} or a {@link TypeAdapterFactory}. Using the factory interface
+ * makes it possible to delegate to the enclosing {@code Gson} instance.
+ *
+ * @since 2.3
+ *
+ * @author Inderjeet Singh
+ * @author Joel Leitch
+ * @author Jesse Wilson
+ */
+// Note that the above example is taken from AdaptAnnotationTest.
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.TYPE, ElementType.FIELD})
+public @interface JsonAdapter {
+
+  /** Either a {@link TypeAdapter} or {@link TypeAdapterFactory}. */
+  Class<?> value();
+
+}