added currency class

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

@@ -232,6 +232,7 @@ public final class Gson {
     factories.add(TypeAdapters.URL_FACTORY);
     factories.add(TypeAdapters.URI_FACTORY);
     factories.add(TypeAdapters.UUID_FACTORY);
+    factories.add(TypeAdapters.CURRENCY_FACTORY);
     factories.add(TypeAdapters.LOCALE_FACTORY);
     factories.add(TypeAdapters.INET_ADDRESS_FACTORY);
     factories.add(TypeAdapters.BIT_SET_FACTORY);

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

@@ -27,6 +27,7 @@ import java.sql.Timestamp;
 import java.util.ArrayList;
 import java.util.BitSet;
 import java.util.Calendar;
+import java.util.Currency;
 import java.util.Date;
 import java.util.GregorianCalendar;
 import java.util.HashMap;
@@ -576,6 +577,18 @@ public final class TypeAdapters {
 
   public static final TypeAdapterFactory UUID_FACTORY = newFactory(UUID.class, UUID);
 
+  public static final TypeAdapter<Currency> CURRENCY = new TypeAdapter<Currency>() {
+    @Override
+    public Currency read(JsonReader in) throws IOException {
+      return Currency.getInstance(in.nextString());
+    }
+    @Override
+    public void write(JsonWriter out, Currency value) throws IOException {
+      out.value(value.getCurrencyCode());
+    }
+  }.nullSafe();
+  public static final TypeAdapterFactory CURRENCY_FACTORY = newFactory(Currency.class, CURRENCY);
+
   public static final TypeAdapterFactory TIMESTAMP_FACTORY = new TypeAdapterFactory() {
     @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
     @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {

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

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 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.functional;
+
+import java.util.Currency;
+
+import com.google.gson.Gson;
+
+import junit.framework.TestCase;
+
+/**
+ * Functional test for Json serialization and deserialization for classes in java.util
+ */
+public class JavaUtilTest extends TestCase {
+  private Gson gson;
+
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    gson = new Gson();
+  }
+
+  public void testCurrency() throws Exception {
+    CurrencyHolder target = gson.fromJson("{'value':'USD'}", CurrencyHolder.class);
+    assertEquals("USD", target.value.getCurrencyCode());
+    String json = gson.toJson(target);
+    assertEquals("{\"value\":\"USD\"}", json);
+
+    // null handling
+    target = gson.fromJson("{'value':null}", CurrencyHolder.class);
+    assertNull(target.value);
+    assertEquals("{}", gson.toJson(target));
+  }
+
+  private static class CurrencyHolder {
+    Currency value;
+  }
+}