Forbid custom serializers for primitive types (so we can avoid boxing in the reflective and array adapters)

gson/GSON 2.0 NOTES.txt

@@ -31,3 +31,9 @@ com.google.gson.functional.PrimitiveTest.testDeserializingBigIntegerAsLong
 GSON 1.x uses arbitrary precision for primitive type conversion (so -122.08e-2132 != 0)
 GSON 2.x uses double precision (so -122.08e-2132 == 0)
 com.google.gson.functional.PrimitiveTest.testDeserializingBigDecimalAsLongFails
+
+
+GSON 1.x supports type adapters for primitive types
+GSON 2.x doesn't
+com.google.gson.functional.CustomTypeAdaptersTest.testCustomSerializerForLong
+com.google.gson.functional.CustomTypeAdaptersTest.testCustomDeserializerForLong

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

@@ -18,7 +18,6 @@ package com.google.gson;
 
 import com.google.gson.DefaultTypeAdapters.DefaultDateTypeAdapter;
 import com.google.gson.internal.$Gson$Preconditions;
-
 import java.lang.reflect.Type;
 import java.sql.Timestamp;
 import java.text.DateFormat;
@@ -495,6 +494,10 @@ public final class GsonBuilder {
   private GsonBuilder registerTypeAdapter(Type type, Object typeAdapter, boolean isSystem) {
     $Gson$Preconditions.checkArgument(typeAdapter instanceof JsonSerializer<?>
         || typeAdapter instanceof JsonDeserializer<?> || typeAdapter instanceof InstanceCreator<?>);
+    if (Primitives.isPrimitive(type) || Primitives.isWrapperType(type)) {
+      throw new IllegalArgumentException(
+          "Cannot register type adapters for " + type);
+    }
     if (typeAdapter instanceof InstanceCreator<?>) {
       registerInstanceCreator(type, (InstanceCreator<?>) typeAdapter, isSystem);
     }

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

@@ -17,13 +17,12 @@
 package com.google.gson;
 
 
+import com.google.gson.internal.$Gson$Preconditions;
 import java.lang.reflect.Type;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
-import com.google.gson.internal.$Gson$Preconditions;
-
 /**
  * Contains static utility methods pertaining to primitive types and their
  * corresponding wrapper types.
@@ -78,7 +77,7 @@ final class Primitives {
    *
    * @see Class#isPrimitive
    */
-  public static boolean isWrapperType(Class<?> type) {
+  public static boolean isWrapperType(Type type) {
     return WRAPPER_TO_PRIMITIVE_TYPE.containsKey(
         $Gson$Preconditions.checkNotNull(type));
   }

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

@@ -173,34 +173,6 @@ public class CustomDeserializerTest extends TestCase {
     assertNull(target.base);
   }
 
-  public void testCustomDeserializerReturnsNullForTopLevelPrimitives() {
-    Gson gson = new GsonBuilder()
-      .registerTypeAdapter(long.class, new JsonDeserializer<Long>() {
-        public Long deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
-            throws JsonParseException {
-          return null;
-        }
-      }).create();
-    String json = "10";
-    assertNull(gson.fromJson(json, long.class));
-  }
-
-  public void testCustomDeserializerReturnsNullForPrimitiveFields() {
-    Gson gson = new GsonBuilder()
-      .registerTypeAdapter(long.class, new JsonDeserializer<Long>() {
-        public Long deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
-            throws JsonParseException {
-          return null;
-        }
-      }).create();
-    String json = "{field:10}";
-    ClassWithLong target = gson.fromJson(json, ClassWithLong.class);
-    assertEquals(0, target.field);
-  }
-  private static class ClassWithLong {
-    long field;
-  }
- 
   public void testCustomDeserializerReturnsNullForArrayElements() {
     Gson gson = new GsonBuilder()
       .registerTypeAdapter(Base.class, new JsonDeserializer<Base>() {

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

@@ -203,59 +203,28 @@ public class CustomTypeAdaptersTest extends TestCase {
     }
   }
 
-  public void testCustomSerializerForLong() {
+  public void testCustomSerializerForbiddenForPrimitives() {
-    final ClassWithBooleanField customSerializerInvoked = new ClassWithBooleanField();
+    try {
-    customSerializerInvoked.value = false;
+      new GsonBuilder().registerTypeAdapter(long.class, new JsonSerializer<Long>() {
-    Gson gson = new GsonBuilder().registerTypeAdapter(Long.class, new JsonSerializer<Long>() {
+        public JsonElement serialize(Long s, Type t, JsonSerializationContext c) {
-      public JsonElement serialize(Long src, Type typeOfSrc, JsonSerializationContext context) {
+          throw new AssertionError();
-        customSerializerInvoked.value = true;
+        }
-        return new JsonPrimitive(src);
+      });
+      fail();
+    } catch (IllegalArgumentException expected) {
     }
-    }).serializeNulls().create();
-    ClassWithWrapperLongField src = new ClassWithWrapperLongField();
-    String json = gson.toJson(src);
-    assertTrue(json.contains("\"value\":null"));
-    assertFalse(customSerializerInvoked.value);
-    
-    customSerializerInvoked.value = false;
-    src.value = 10L;
-    json = gson.toJson(src);
-    assertTrue(json.contains("\"value\":10"));
-    assertTrue(customSerializerInvoked.value);
   }
 
-  public void testCustomDeserializerForLong() {
+  public void testCustomDeserializerForbiddenForPrimitives() {
-    final ClassWithBooleanField customDeserializerInvoked = new ClassWithBooleanField();
+    try {
-    customDeserializerInvoked.value = false;
+      new GsonBuilder().registerTypeAdapter(long.class, new JsonDeserializer<Long>() {
-    Gson gson = new GsonBuilder().registerTypeAdapter(Long.class, new JsonDeserializer<Long>() {
+        public Long deserialize(JsonElement json, Type t, JsonDeserializationContext c) {
-      public Long deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
+          throw new AssertionError();
-          throws JsonParseException {
-        customDeserializerInvoked.value = true;
-        if (json == null || json.isJsonNull()) {
-          return null;
         }
-        Number number = json.getAsJsonPrimitive().getAsNumber();
+      });
-        return number == null ? null : number.longValue();
+      fail();
+    } catch (Exception expected) {
     }
-    }).create();
-    String json = "{'value':null}";
-    ClassWithWrapperLongField target = gson.fromJson(json, ClassWithWrapperLongField.class);
-    assertNull(target.value);
-    assertFalse(customDeserializerInvoked.value);
-    
-    customDeserializerInvoked.value = false;
-    json = "{'value':10}";
-    target = gson.fromJson(json, ClassWithWrapperLongField.class);
-    assertEquals(10L, target.value.longValue());
-    assertTrue(customDeserializerInvoked.value);
-  }
-  
-  private static class ClassWithWrapperLongField {
-    Long value;
-  }
-  
-  private static class ClassWithBooleanField {
-    Boolean value;
   }
 
   public void testCustomByteArraySerializer() {