diff --git a/gson/src/main/java/com/google/gson/DefaultDateTypeAdapter.java b/gson/src/main/java/com/google/gson/DefaultDateTypeAdapter.java
index 81700e63..35b80305 100644
--- a/gson/src/main/java/com/google/gson/DefaultDateTypeAdapter.java
+++ b/gson/src/main/java/com/google/gson/DefaultDateTypeAdapter.java
@@ -24,7 +24,6 @@ import java.text.ParsePosition;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Locale;
-import java.util.TimeZone;
 
 import com.google.gson.internal.bind.util.ISO8601Utils;
 
diff --git a/gson/src/main/java/com/google/gson/internal/Streams.java b/gson/src/main/java/com/google/gson/internal/Streams.java
index 74956d77..ac99910a 100644
--- a/gson/src/main/java/com/google/gson/internal/Streams.java
+++ b/gson/src/main/java/com/google/gson/internal/Streams.java
@@ -72,7 +72,6 @@ public final class Streams {
     TypeAdapters.JSON_ELEMENT.write(writer, element);
   }
 
-  @SuppressWarnings("resource")
   public static Writer writerForAppendable(Appendable appendable) {
     return appendable instanceof Writer ? (Writer) appendable : new AppendableWriter(appendable);
   }
diff --git a/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java b/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java
index b47aaac4..9d9f6be8 100644
--- a/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java
+++ b/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java
@@ -32,6 +32,7 @@ import com.google.gson.reflect.TypeToken;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonToken;
 import com.google.gson.stream.JsonWriter;
+
 import java.io.IOException;
 import java.lang.reflect.Field;
 import java.lang.reflect.Type;
@@ -104,14 +105,22 @@ public final class ReflectiveTypeAdapterFactory implements TypeAdapterFactory {
       final TypeToken<?> fieldType, boolean serialize, boolean deserialize) {
     final boolean isPrimitive = Primitives.isPrimitive(fieldType.getRawType());
     // special casing primitives here saves ~5% on Android...
+    JsonAdapter annotation = field.getAnnotation(JsonAdapter.class);
+    TypeAdapter<?> mapped = null;
+    if (annotation != null) {
+      mapped = getTypeAdapter(constructorConstructor, context, fieldType, annotation);
+    }
+    final boolean jsonAdapterPresent = mapped != null;
+    if (mapped == null) mapped = context.getAdapter(fieldType);
+
+    final TypeAdapter<?> typeAdapter = mapped;
     return new ReflectiveTypeAdapterFactory.BoundField(name, serialize, deserialize) {
-      final TypeAdapter<?> typeAdapter = getFieldAdapter(context, field, fieldType);
       @SuppressWarnings({"unchecked", "rawtypes"}) // the type adapter and field type always agree
       @Override void write(JsonWriter writer, Object value)
           throws IOException, IllegalAccessException {
         Object fieldValue = field.get(value);
-        TypeAdapter t =
-          new TypeAdapterRuntimeTypeWrapper(context, this.typeAdapter, fieldType.getType());
+        TypeAdapter t = jsonAdapterPresent ? typeAdapter
+            : new TypeAdapterRuntimeTypeWrapper(context, typeAdapter, fieldType.getType());
         t.write(writer, fieldValue);
       }
       @Override void read(JsonReader reader, Object value)
@@ -129,15 +138,6 @@ public final class ReflectiveTypeAdapterFactory implements TypeAdapterFactory {
     };
   }
 
-  TypeAdapter<?> getFieldAdapter(Gson gson, Field field, TypeToken<?> fieldType) {
-    JsonAdapter annotation = field.getAnnotation(JsonAdapter.class);
-    if (annotation != null) {
-      TypeAdapter<?> adapter = getTypeAdapter(constructorConstructor, gson, fieldType, annotation);
-      if (adapter != null) return adapter;
-    }
-    return gson.getAdapter(fieldType);
-  }
-
   private Map<String, BoundField> getBoundFields(Gson context, TypeToken<?> type, Class<?> raw) {
     Map<String, BoundField> result = new LinkedHashMap<String, BoundField>();
     if (raw.isInterface()) {
diff --git a/gson/src/main/java/com/google/gson/internal/bind/TypeAdapterRuntimeTypeWrapper.java b/gson/src/main/java/com/google/gson/internal/bind/TypeAdapterRuntimeTypeWrapper.java
index 7e52c27d..2bf37ad0 100644
--- a/gson/src/main/java/com/google/gson/internal/bind/TypeAdapterRuntimeTypeWrapper.java
+++ b/gson/src/main/java/com/google/gson/internal/bind/TypeAdapterRuntimeTypeWrapper.java
@@ -15,14 +15,15 @@
  */
 package com.google.gson.internal.bind;
 
+import java.io.IOException;
+import java.lang.reflect.Type;
+import java.lang.reflect.TypeVariable;
+
 import com.google.gson.Gson;
 import com.google.gson.TypeAdapter;
 import com.google.gson.reflect.TypeToken;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
-import java.io.IOException;
-import java.lang.reflect.Type;
-import java.lang.reflect.TypeVariable;
 
 final class TypeAdapterRuntimeTypeWrapper<T> extends TypeAdapter<T> {
   private final Gson context;
diff --git a/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnFieldsTest.java b/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnFieldsTest.java
index 4c745ec2..6f4a0ce9 100644
--- a/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnFieldsTest.java
+++ b/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnFieldsTest.java
@@ -63,7 +63,6 @@ public final class JsonAdapterAnnotationOnFieldsTest extends TestCase {
         @Override public void write(JsonWriter out, Part part) throws IOException {
           throw new AssertionError();
         }
-
         @Override public Part read(JsonReader in) throws IOException {
           throw new AssertionError();
         }
@@ -220,4 +219,53 @@ public final class JsonAdapterAnnotationOnFieldsTest extends TestCase {
       this.part = part;
     }
   }
+
+  /** Regression test contributed through https://github.com/google/gson/issues/831 */
+  public void testNonPrimitiveFieldAnnotationTakesPrecedenceOverDefault() {
+    Gson gson = new Gson();
+    String json = gson.toJson(new GadgetWithOptionalPart(new Part("foo")));
+    assertEquals("{\"part\":\"PartJsonFieldAnnotationAdapter\"}", json);
+    GadgetWithOptionalPart gadget = gson.fromJson("{'part':'foo'}", GadgetWithOptionalPart.class);
+    assertEquals("PartJsonFieldAnnotationAdapter", gadget.part.name);
+  }
+
+  /** Regression test contributed through https://github.com/google/gson/issues/831 */
+  public void testPrimitiveFieldAnnotationTakesPrecedenceOverDefault() {
+    Gson gson = new Gson();
+    String json = gson.toJson(new GadgetWithPrimitivePart(42));
+    assertEquals("{\"part\":\"42\"}", json);
+    GadgetWithPrimitivePart gadget = gson.fromJson(json, GadgetWithPrimitivePart.class);
+    assertEquals(42, gadget.part);
+  }
+
+  private static final class GadgetWithPrimitivePart {
+    @JsonAdapter(LongToStringTypeAdapterFactory.class)
+    final long part;
+
+    private GadgetWithPrimitivePart(long part) {
+      this.part = part;
+    }
+  }
+
+  private static final class LongToStringTypeAdapterFactory implements TypeAdapterFactory {
+    static final TypeAdapter<Long> ADAPTER = new TypeAdapter<Long>() {
+      @Override public void write(JsonWriter out, Long value) throws IOException {
+        out.value(value.toString());
+      }
+      @Override public Long read(JsonReader in) throws IOException {
+        return in.nextLong();
+      }
+    };
+    @SuppressWarnings("unchecked")
+    @Override public <T> TypeAdapter<T> create(Gson gson, final TypeToken<T> type) {
+      Class<?> cls = type.getRawType();
+      if (Long.class.isAssignableFrom(cls)) {
+        return (TypeAdapter<T>) ADAPTER;
+      } else if (long.class.isAssignableFrom(cls)) {
+        return (TypeAdapter<T>) ADAPTER;
+      }
+      throw new IllegalStateException("Non-long field of type " + type
+          + " annotated with @JsonAdapter(LongToStringTypeAdapterFactory.class)");
+    }
+  }
 }