Check for JSONObject.NULL before casting to String [Fixes #209]

Author: jhansche

Parse/src/main/java/com/parse/ParseDecoder.java

@@ -71,6 +71,10 @@ public Object decode(Object object) {
       return convertJSONArrayToList((JSONArray) object);
     }
 
+    if (object == JSONObject.NULL) {
+      return null;
+    }
+
     if (!(object instanceof JSONObject)) {
       return object;
     }

Parse/src/test/java/com/parse/ParseDecoderTest.java

@@ -73,6 +73,12 @@ public void testNonJSONObject() {
     assertSame(obj, ParseDecoder.get().decode(obj));
   }
 
+  @Test
+  public void testNull() {
+    Object object = ParseDecoder.get().decode(JSONObject.NULL);
+    assertNull(object);
+  }
+
   @Test
   public void testParseFieldOperations() throws JSONException {
     JSONObject json = new JSONObject();