From 933a3e515021e9d3dea4a18326479a42df353494 Mon Sep 17 00:00:00 2001
From: Joel Leitch <joel.leitch@gmail.com>
Date: Tue, 29 Sep 2009 20:34:35 +0000
Subject: [PATCH] Allow serialization of nulls in a "List<Object>" type.

---
 .../java/com/google/gson/DefaultTypeAdapters.java    | 12 ++++++++----
 .../com/google/gson/functional/CollectionTest.java   | 11 +++++++++++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/gson/src/main/java/com/google/gson/DefaultTypeAdapters.java b/gson/src/main/java/com/google/gson/DefaultTypeAdapters.java
index 60db44d8..fd0d874e 100644
--- a/gson/src/main/java/com/google/gson/DefaultTypeAdapters.java
+++ b/gson/src/main/java/com/google/gson/DefaultTypeAdapters.java
@@ -443,10 +443,14 @@ final class DefaultTypeAdapters {
         childGenericType = new TypeInfoCollection(typeOfSrc).getElementType();        
       }
       for (Object child : src) {
-        Type childType = (childGenericType == null || childGenericType == Object.class)
-            ? child.getClass() : childGenericType;
-        JsonElement element = context.serialize(child, childType);
-        array.add(element);
+        if (child == null) {
+          array.add(JsonNull.createJsonNull());
+        } else {
+          Type childType = (childGenericType == null || childGenericType == Object.class)
+              ? child.getClass() : childGenericType;
+          JsonElement element = context.serialize(child, childType);
+          array.add(element);
+        }
       }
       return array;
     }
diff --git a/gson/src/test/java/com/google/gson/functional/CollectionTest.java b/gson/src/test/java/com/google/gson/functional/CollectionTest.java
index d43d4ce2..9889c050 100644
--- a/gson/src/test/java/com/google/gson/functional/CollectionTest.java
+++ b/gson/src/test/java/com/google/gson/functional/CollectionTest.java
@@ -153,6 +153,17 @@ public class CollectionTest extends TestCase {
     Type type = new TypeToken<List<Object>>() {}.getType();
     assertEquals("[\"Hello\",\"World\"]", gson.toJson(target, type));
   }
+  
+  public void testCollectionOfObjectWithNullSerialization() {
+    List<Object> target = new ArrayList<Object>();
+    target.add("Hello");
+    target.add(null);
+    target.add("World");
+    assertEquals("[\"Hello\",null,\"World\"]", gson.toJson(target));
+    
+    Type type = new TypeToken<List<Object>>() {}.getType();
+    assertEquals("[\"Hello\",null,\"World\"]", gson.toJson(target, type));
+  }
 
   public void testCollectionOfStringsSerialization() {
     List<String> target = new ArrayList<String>();