Converted EnumTypeAdapter to new style.

Got rid of default Hierarchy Serializer/Deserializers from DefaultTypeAdapters.
Got rid of methods for gettting default serializers/deserializers/instance creators. Instead we reuse the static final instances.
Fixed warnings in TypeAdapters where a parameterized type T was hiding the parameterized T in methods.
Removed support to unwrap single element array of enums into enum values. Also removed the test that verifies this behavior.

gson/GSON 2.0 NOTES.txt

@@ -11,6 +11,7 @@ com.google.gson.functional.PrimitiveTest.testPrimitiveDoubleAutoboxedInASingleEl
 com.google.gson.functional.PrimitiveTest.testBigDecimalInASingleElementArrayDeserialization
 com.google.gson.functional.PrimitiveTest.testBigIntegerInASingleElementArrayDeserialization
 com.google.gson.functional.StringTest.testStringValueAsSingleElementArrayDeserialization
+com.google.gson.functional.EnumTest.testTopLevelEnumInASingleElementArrayDeserialization
 
 GSON 1.x permitted primitive types to be overridden
 GSON 2.x doesn't.

gson/src/main/java/com/google/gson/DefaultTypeAdapters.java

@@ -47,9 +47,6 @@ final class DefaultTypeAdapters {
   private static final DefaultTimestampDeserializer TIMESTAMP_DESERIALIZER =
     new DefaultTimestampDeserializer();
 
-  @SuppressWarnings("unchecked")
-  private static final EnumTypeAdapter ENUM_TYPE_ADAPTER = new EnumTypeAdapter();
-
   private static final CharacterTypeAdapter CHARACTER_TYPE_ADAPTER = new CharacterTypeAdapter();
   private static final NumberTypeAdapter NUMBER_TYPE_ADAPTER = new NumberTypeAdapter();
 
@@ -59,15 +56,11 @@ final class DefaultTypeAdapters {
   // The constants DEFAULT_SERIALIZERS, DEFAULT_DESERIALIZERS, and DEFAULT_INSTANCE_CREATORS
   // must be defined after the constants for the type adapters. Otherwise, the type adapter
   // constants will appear as nulls.
-  private static final ParameterizedTypeHandlerMap<JsonSerializer<?>> DEFAULT_SERIALIZERS =
+  static final ParameterizedTypeHandlerMap<JsonSerializer<?>> DEFAULT_SERIALIZERS =
       createDefaultSerializers();
-  static final ParameterizedTypeHandlerMap<JsonSerializer<?>> DEFAULT_HIERARCHY_SERIALIZERS =
+  static final ParameterizedTypeHandlerMap<JsonDeserializer<?>> DEFAULT_DESERIALIZERS =
-      createDefaultHierarchySerializers();
-  private static final ParameterizedTypeHandlerMap<JsonDeserializer<?>> DEFAULT_DESERIALIZERS =
       createDefaultDeserializers();
-  static final ParameterizedTypeHandlerMap<JsonDeserializer<?>> DEFAULT_HIERARCHY_DESERIALIZERS =
+  static final ParameterizedTypeHandlerMap<InstanceCreator<?>> DEFAULT_INSTANCE_CREATORS =
-      createDefaultHierarchyDeserializers();
-  private static final ParameterizedTypeHandlerMap<InstanceCreator<?>> DEFAULT_INSTANCE_CREATORS =
       createDefaultInstanceCreators();
 
   private static ParameterizedTypeHandlerMap<JsonSerializer<?>> createDefaultSerializers() {
@@ -89,14 +82,6 @@ final class DefaultTypeAdapters {
     return map;
   }
 
-  private static ParameterizedTypeHandlerMap<JsonSerializer<?>> createDefaultHierarchySerializers() {
-    ParameterizedTypeHandlerMap<JsonSerializer<?>> map =
-        new ParameterizedTypeHandlerMap<JsonSerializer<?>>();
-    map.registerForTypeHierarchy(Enum.class, ENUM_TYPE_ADAPTER, true);
-    map.makeUnmodifiable();
-    return map;
-  }
-
   private static ParameterizedTypeHandlerMap<JsonDeserializer<?>> createDefaultDeserializers() {
     ParameterizedTypeHandlerMap<JsonDeserializer<?>> map =
         new ParameterizedTypeHandlerMap<JsonDeserializer<?>>();
@@ -115,14 +100,6 @@ final class DefaultTypeAdapters {
     return map;
   }
 
-  private static ParameterizedTypeHandlerMap<JsonDeserializer<?>> createDefaultHierarchyDeserializers() {
-    ParameterizedTypeHandlerMap<JsonDeserializer<?>> map =
-        new ParameterizedTypeHandlerMap<JsonDeserializer<?>>();
-    map.registerForTypeHierarchy(Enum.class, wrapDeserializer(ENUM_TYPE_ADAPTER), true);
-    map.makeUnmodifiable();
-    return map;
-  }
-
   private static ParameterizedTypeHandlerMap<InstanceCreator<?>> createDefaultInstanceCreators() {
     ParameterizedTypeHandlerMap<InstanceCreator<?>> map
         = new ParameterizedTypeHandlerMap<InstanceCreator<?>>();
@@ -135,32 +112,6 @@ final class DefaultTypeAdapters {
     return new JsonDeserializerExceptionWrapper(deserializer);
   }
 
-  static ParameterizedTypeHandlerMap<JsonSerializer<?>> getDefaultSerializers() {
-    return DEFAULT_SERIALIZERS.copyOf();
-  }
-
-  static ParameterizedTypeHandlerMap<JsonSerializer<?>> getAllDefaultSerializers() {
-    ParameterizedTypeHandlerMap<JsonSerializer<?>> defaultSerializers =
-      DEFAULT_SERIALIZERS.copyOf();
-    defaultSerializers.register(DEFAULT_HIERARCHY_SERIALIZERS);
-    return defaultSerializers;
-  }
-
-  static ParameterizedTypeHandlerMap<JsonDeserializer<?>> getAllDefaultDeserializers() {
-    ParameterizedTypeHandlerMap<JsonDeserializer<?>> defaultDeserializers =
-      getDefaultDeserializers().copyOf();
-    defaultDeserializers.register(DEFAULT_HIERARCHY_DESERIALIZERS);
-    return defaultDeserializers;
-  }
-
-  static ParameterizedTypeHandlerMap<JsonDeserializer<?>> getDefaultDeserializers() {
-    return DEFAULT_DESERIALIZERS;
-  }
-
-  static ParameterizedTypeHandlerMap<InstanceCreator<?>> getDefaultInstanceCreators() {
-    return DEFAULT_INSTANCE_CREATORS;
-  }
-
   /**
    * This type adapter supports three subclasses of date: Date, Timestamp, and
    * java.sql.Date.
@@ -354,25 +305,6 @@ final class DefaultTypeAdapters {
     }
   }
 
-  @SuppressWarnings("unchecked")
-  private static final class EnumTypeAdapter<T extends Enum<T>>
-      implements JsonSerializer<T>, JsonDeserializer<T> {
-    public JsonElement serialize(T src, Type typeOfSrc, JsonSerializationContext context) {
-      return new JsonPrimitive(src.name());
-    }
-
-    @SuppressWarnings("cast")
-    public T deserialize(JsonElement json, Type classOfT, JsonDeserializationContext context)
-        throws JsonParseException {
-      return (T) Enum.valueOf((Class<T>) classOfT, json.getAsString());
-    }
-
-    @Override
-    public String toString() {
-      return EnumTypeAdapter.class.getSimpleName();
-    }
-  }
-
   private static final class NumberTypeAdapter
       implements JsonSerializer<Number>, JsonDeserializer<Number> {
     public JsonElement serialize(Number src, Type typeOfSrc, JsonSerializationContext context) {

gson/src/main/java/com/google/gson/Gson.java

@@ -168,9 +168,9 @@ public final class Gson {
    */
   public Gson() {
     this(DEFAULT_EXCLUSION_STRATEGY, DEFAULT_EXCLUSION_STRATEGY, DEFAULT_NAMING_POLICY,
-        DefaultTypeAdapters.getDefaultInstanceCreators(),
+        DefaultTypeAdapters.DEFAULT_INSTANCE_CREATORS,
-        false, DefaultTypeAdapters.getAllDefaultSerializers(),
+        false, DefaultTypeAdapters.DEFAULT_SERIALIZERS,
-        DefaultTypeAdapters.getAllDefaultDeserializers(), false, DEFAULT_JSON_NON_EXECUTABLE, true,
+        DefaultTypeAdapters.DEFAULT_DESERIALIZERS, false, DEFAULT_JSON_NON_EXECUTABLE, true,
         false, false, LongSerializationPolicy.DEFAULT);
   }
 
@@ -254,6 +254,7 @@ public final class Gson {
         ))
         .factory(new MapTypeAdapterFactory(constructorConstructor, complexMapKeySerialization))
         .factory(ArrayTypeAdapter.FACTORY)
+        .factory(TypeAdapters.ENUM_FACTORY)
         .factory(reflectiveTypeAdapterFactory);
 
     this.miniGson = builder.build();

gson/src/main/java/com/google/gson/GsonBuilder.java

@@ -669,21 +669,17 @@ public final class GsonBuilder {
       serializationStrategies.add(exposeAnnotationSerializationExclusionStrategy);
     }
 
-    ParameterizedTypeHandlerMap<JsonSerializer<?>> customSerializers =
+    ParameterizedTypeHandlerMap<JsonSerializer<?>> customSerializers = serializers.copyOf();
-        DefaultTypeAdapters.DEFAULT_HIERARCHY_SERIALIZERS.copyOf();
+    ParameterizedTypeHandlerMap<JsonDeserializer<?>> customDeserializers = deserializers.copyOf();
-    customSerializers.register(serializers.copyOf());
-    ParameterizedTypeHandlerMap<JsonDeserializer<?>> customDeserializers =
-        DefaultTypeAdapters.DEFAULT_HIERARCHY_DESERIALIZERS.copyOf();
-    customDeserializers.register(deserializers.copyOf());
     addTypeAdaptersForDate(datePattern, dateStyle, timeStyle, customSerializers,
         customDeserializers);
 
-    customSerializers.registerIfAbsent(DefaultTypeAdapters.getDefaultSerializers());
+    customSerializers.registerIfAbsent(DefaultTypeAdapters.DEFAULT_SERIALIZERS);
-    customDeserializers.registerIfAbsent(DefaultTypeAdapters.getDefaultDeserializers());
+    customDeserializers.registerIfAbsent(DefaultTypeAdapters.DEFAULT_DESERIALIZERS);
 
     ParameterizedTypeHandlerMap<InstanceCreator<?>> customInstanceCreators =
         instanceCreators.copyOf();
-    customInstanceCreators.registerIfAbsent(DefaultTypeAdapters.getDefaultInstanceCreators());
+    customInstanceCreators.registerIfAbsent(DefaultTypeAdapters.DEFAULT_INSTANCE_CREATORS);
 
     customSerializers.makeUnmodifiable();
     customDeserializers.makeUnmodifiable();

gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java

@@ -401,8 +401,36 @@ public final class TypeAdapters {
 
   public static final TypeAdapter.Factory LOCALE_FACTORY = newFactory(Locale.class, LOCALE);
 
-  public static <T> TypeAdapter.Factory newFactory(
+  private static final class EnumTypeAdapter<T extends Enum<T>> extends TypeAdapter<T> {
-      final TypeToken<T> type, final TypeAdapter<T> typeAdapter) {
+    private final Class<T> classOfT;
+
+    public EnumTypeAdapter(Class<T> classOfT) {
+      this.classOfT = classOfT;
+    }
+    public T read(JsonReader reader) throws IOException {
+      return (T) Enum.valueOf((Class<T>) classOfT, reader.nextString());
+    }
+
+    public void write(JsonWriter writer, T src) throws IOException {
+      writer.value(src.name());
+    }
+  };
+
+  public static final TypeAdapter.Factory ENUM_FACTORY = newEnumTypeHierarchyFactory(Enum.class);
+
+  public static <TT> TypeAdapter.Factory newEnumTypeHierarchyFactory(final Class<TT> clazz) {
+    return new TypeAdapter.Factory() {
+      @SuppressWarnings("unchecked")
+      public <T> TypeAdapter<T> create(MiniGson context, TypeToken<T> typeToken) {
+        Class<? super T> rawType = typeToken.getRawType();
+        return clazz.isAssignableFrom(rawType)
+          ? (TypeAdapter<T>) new EnumTypeAdapter(rawType) : null;
+      }
+    };
+  }
+
+  public static <TT> TypeAdapter.Factory newFactory(
+      final TypeToken<TT> type, final TypeAdapter<TT> typeAdapter) {
     return new TypeAdapter.Factory() {
       @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
       public <T> TypeAdapter<T> create(MiniGson context, TypeToken<T> typeToken) {
@@ -411,8 +439,8 @@ public final class TypeAdapters {
     };
   }
 
-  public static <T> TypeAdapter.Factory newFactory(
+  public static <TT> TypeAdapter.Factory newFactory(
-      final Class<T> type, final TypeAdapter<T> typeAdapter) {
+      final Class<TT> type, final TypeAdapter<TT> typeAdapter) {
     return new TypeAdapter.Factory() {
       @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
       public <T> TypeAdapter<T> create(MiniGson context, TypeToken<T> typeToken) {
@@ -421,8 +449,8 @@ public final class TypeAdapters {
     };
   }
 
-  public static <T> TypeAdapter.Factory newFactory(
+  public static <TT> TypeAdapter.Factory newFactory(
-      final Class<T> unboxed, final Class<T> boxed, final TypeAdapter<? super T> typeAdapter) {
+      final Class<TT> unboxed, final Class<TT> boxed, final TypeAdapter<? super TT> typeAdapter) {
     return new TypeAdapter.Factory() {
       @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
       public <T> TypeAdapter<T> create(MiniGson context, TypeToken<T> typeToken) {
@@ -432,9 +460,10 @@ public final class TypeAdapters {
     };
   }
 
-  public static <T> TypeAdapter.Factory newTypeHierarchyFactory(
+  public static <TT> TypeAdapter.Factory newTypeHierarchyFactory(
-      final Class<T> clazz, final TypeAdapter<T> typeAdapter) {
+      final Class<TT> clazz, final TypeAdapter<TT> typeAdapter) {
     return new TypeAdapter.Factory() {
+      @SuppressWarnings("unchecked")
       public <T> TypeAdapter<T> create(MiniGson context, TypeToken<T> typeToken) {
         return clazz.isAssignableFrom(typeToken.getRawType()) ? (TypeAdapter<T>) typeAdapter : null;
       }

gson/src/test/java/com/google/gson/FunctionWithInternalDependenciesTest.java

@@ -37,9 +37,9 @@ public class FunctionWithInternalDependenciesTest extends TestCase {
     strategies.add(new ModifierBasedExclusionStrategy(Modifier.TRANSIENT, Modifier.STATIC));
     ExclusionStrategy exclusionStrategy = new DisjunctionExclusionStrategy(strategies);
     Gson gson = new Gson(exclusionStrategy, exclusionStrategy, Gson.DEFAULT_NAMING_POLICY,
-        DefaultTypeAdapters.getDefaultInstanceCreators(),
+        DefaultTypeAdapters.DEFAULT_INSTANCE_CREATORS,
-        false, DefaultTypeAdapters.getDefaultSerializers(),
+        false, DefaultTypeAdapters.DEFAULT_SERIALIZERS,
-        DefaultTypeAdapters.getDefaultDeserializers(), false, Gson.DEFAULT_JSON_NON_EXECUTABLE,
+        DefaultTypeAdapters.DEFAULT_DESERIALIZERS, false, Gson.DEFAULT_JSON_NON_EXECUTABLE,
         true, false, false, LongSerializationPolicy.DEFAULT);
     assertEquals("{}", gson.toJson(new ClassWithNoFields() {
       // empty anonymous class

gson/src/test/java/com/google/gson/functional/EnumTest.java

@@ -62,12 +62,6 @@ public class EnumTest extends TestCase {
     assertEquals(MyEnum.VALUE1, result);
   }
 
-  public void testTopLevelEnumInASingleElementArrayDeserialization() {
-    String json = "[" + MyEnum.VALUE1.getExpectedJson() + "]";
-    MyEnum target = gson.fromJson(json, MyEnum.class);
-    assertEquals(json, "[" + target.getExpectedJson() + "]");
-  }
-
   public void testCollectionOfEnumsSerialization() {
     Type type = new TypeToken<Collection<MyEnum>>() {}.getType();
     Collection<MyEnum> target = new ArrayList<MyEnum>();