diff --git a/apps/vtn/vtnweb/src/main/java/org/onosproject/vtnweb/resources/RouterWebResource.java b/apps/vtn/vtnweb/src/main/java/org/onosproject/vtnweb/resources/RouterWebResource.java
index 855209c..332bd41 100644
--- a/apps/vtn/vtnweb/src/main/java/org/onosproject/vtnweb/resources/RouterWebResource.java
+++ b/apps/vtn/vtnweb/src/main/java/org/onosproject/vtnweb/resources/RouterWebResource.java
@@ -106,7 +106,7 @@
                 .getRouter(RouterId.valueOf(id)), NOT_EXIST);
 
         ObjectNode result = new ObjectMapper().createObjectNode();
-        if (fields.size() > 0) {
+        if (!fields.isEmpty()) {
             result.set("router",
                        new RouterCodec().extracFields(sub, this, fields));
         } else {