From d129f10229869bb8be3aff0787cd6303eb0e5ad0 Mon Sep 17 00:00:00 2001
From: Igor Suhorukov <igor.suhorukov@gmail.com>
Date: Thu, 8 Feb 2018 11:20:00 +0300
Subject: [PATCH] Collection.isEmpty() should be used to test for emptiness
 (#1315)

---
 .../cluster/directory/AbstractDirectory.java  |  2 +-
 .../cluster/directory/StaticDirectory.java    |  4 ++--
 .../loadbalance/AbstractLoadBalance.java      |  2 +-
 .../router/condition/ConditionRouter.java     | 14 ++++++------
 .../support/AbstractClusterInvoker.java       | 16 +++++++-------
 .../support/MergeableClusterInvoker.java      |  2 +-
 .../support/wrapper/MockClusterInvoker.java   |  2 +-
 .../java/com/alibaba/dubbo/common/URL.java    |  2 +-
 .../common/extension/ExtensionLoader.java     |  6 ++---
 .../factory/SpiExtensionFactory.java          |  2 +-
 .../dubbo/common/utils/CollectionUtils.java   |  8 +++----
 .../dubbo/common/utils/ConfigUtils.java       |  2 +-
 .../alibaba/dubbo/common/utils/UrlUtils.java  |  2 +-
 .../dubbo/config/AbstractInterfaceConfig.java | 10 ++++-----
 .../dubbo/config/AbstractServiceConfig.java   |  2 +-
 .../dubbo/config/ApplicationConfig.java       |  2 +-
 .../alibaba/dubbo/config/ModuleConfig.java    |  2 +-
 .../alibaba/dubbo/config/ReferenceConfig.java |  8 +++----
 .../alibaba/dubbo/config/ServiceConfig.java   | 20 ++++++++---------
 .../dubbo/config/spring/ReferenceBean.java    |  8 +++----
 .../dubbo/config/spring/ServiceBean.java      | 16 +++++++-------
 .../support/jvalidation/JValidator.java       |  2 +-
 .../integration/RegistryDirectory.java        | 22 +++++++++----------
 .../status/RegistryStatusChecker.java         |  2 +-
 .../registry/support/AbstractRegistry.java    |  6 ++---
 .../registry/support/FailbackRegistry.java    |  6 ++---
 .../registry/multicast/MulticastRegistry.java | 10 ++++-----
 .../dubbo/registry/redis/RedisRegistry.java   | 12 +++++-----
 .../registry/zookeeper/ZookeeperRegistry.java |  4 ++--
 .../support/header/HeaderExchangeServer.java  |  2 +-
 .../remoting/telnet/codec/TelnetCodec.java    |  6 ++---
 .../support/command/HelpTelnetHandler.java    |  2 +-
 .../support/command/StatusTelnetHandler.java  |  2 +-
 .../remoting/transport/AbstractServer.java    |  2 +-
 .../transport/ChannelHandlerDispatcher.java   |  2 +-
 .../remoting/transport/netty/NettyServer.java |  2 +-
 .../com/alibaba/dubbo/rpc/RpcContext.java     |  2 +-
 .../rpc/listener/ListenerExporterWrapper.java |  4 ++--
 .../rpc/listener/ListenerInvokerWrapper.java  |  4 ++--
 .../rpc/protocol/ProtocolFilterWrapper.java   |  2 +-
 .../protocol/dubbo/filter/TraceFilter.java    |  4 ++--
 .../dubbo/status/ServerStatusChecker.java     |  2 +-
 42 files changed, 116 insertions(+), 116 deletions(-)

diff --git a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/directory/AbstractDirectory.java b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/directory/AbstractDirectory.java
index f4b8aa956b..db787747f5 100644
--- a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/directory/AbstractDirectory.java
+++ b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/directory/AbstractDirectory.java
@@ -72,7 +72,7 @@ public abstract class AbstractDirectory<T> implements Directory<T> {
         }
         List<Invoker<T>> invokers = doList(invocation);
         List<Router> localRouters = this.routers; // local reference
-        if (localRouters != null && localRouters.size() > 0) {
+        if (localRouters != null && !localRouters.isEmpty()) {
             for (Router router : localRouters) {
                 try {
                     if (router.getUrl() == null || router.getUrl().getParameter(Constants.RUNTIME_KEY, false)) {
diff --git a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/directory/StaticDirectory.java b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/directory/StaticDirectory.java
index 1d183a4ad7..a8563b643c 100644
--- a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/directory/StaticDirectory.java
+++ b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/directory/StaticDirectory.java
@@ -45,8 +45,8 @@ public class StaticDirectory<T> extends AbstractDirectory<T> {
     }
 
     public StaticDirectory(URL url, List<Invoker<T>> invokers, List<Router> routers) {
-        super(url == null && invokers != null && invokers.size() > 0 ? invokers.get(0).getUrl() : url, routers);
-        if (invokers == null || invokers.size() == 0)
+        super(url == null && invokers != null && !invokers.isEmpty() ? invokers.get(0).getUrl() : url, routers);
+        if (invokers == null || invokers.isEmpty())
             throw new IllegalArgumentException("invokers == null");
         this.invokers = invokers;
     }
diff --git a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/loadbalance/AbstractLoadBalance.java b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/loadbalance/AbstractLoadBalance.java
index 776b3f6478..74db7bcd18 100644
--- a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/loadbalance/AbstractLoadBalance.java
+++ b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/loadbalance/AbstractLoadBalance.java
@@ -36,7 +36,7 @@ public abstract class AbstractLoadBalance implements LoadBalance {
     }
 
     public <T> Invoker<T> select(List<Invoker<T>> invokers, URL url, Invocation invocation) {
-        if (invokers == null || invokers.size() == 0)
+        if (invokers == null || invokers.isEmpty())
             return null;
         if (invokers.size() == 1)
             return invokers.get(0);
diff --git a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/router/condition/ConditionRouter.java b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/router/condition/ConditionRouter.java
index c3b58452ea..927849f4eb 100644
--- a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/router/condition/ConditionRouter.java
+++ b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/router/condition/ConditionRouter.java
@@ -127,7 +127,7 @@ public class ConditionRouter implements Router, Comparable<Router> {
             }
             // The Value in the KV part, if Value have more than one items.
             else if (",".equals(separator)) { // Should be seperateed by ','
-                if (values == null || values.size() == 0)
+                if (values == null || values.isEmpty())
                     throw new ParseException("Illegal route rule \""
                             + rule + "\", The error char '" + separator
                             + "' at index " + matcher.start() + " before \""
@@ -144,7 +144,7 @@ public class ConditionRouter implements Router, Comparable<Router> {
 
     public <T> List<Invoker<T>> route(List<Invoker<T>> invokers, URL url, Invocation invocation)
             throws RpcException {
-        if (invokers == null || invokers.size() == 0) {
+        if (invokers == null || invokers.isEmpty()) {
             return invokers;
         }
         try {
@@ -161,7 +161,7 @@ public class ConditionRouter implements Router, Comparable<Router> {
                     result.add(invoker);
                 }
             }
-            if (result.size() > 0) {
+            if (!result.isEmpty()) {
                 return result;
             } else if (force) {
                 logger.warn("The route result is empty and force execute. consumer: " + NetUtils.getLocalHost() + ", service: " + url.getServiceKey() + ", router: " + url.getParameterAndDecoded(Constants.RULE_KEY));
@@ -216,7 +216,7 @@ public class ConditionRouter implements Router, Comparable<Router> {
                 }
             } else {
                 //not pass the condition
-                if (matchPair.getValue().matches.size() > 0) {
+                if (!matchPair.getValue().matches.isEmpty()) {
                     return false;
                 } else {
                     result = true;
@@ -231,7 +231,7 @@ public class ConditionRouter implements Router, Comparable<Router> {
         final Set<String> mismatches = new HashSet<String>();
 
         private boolean isMatch(String value, URL param) {
-            if (matches.size() > 0 && mismatches.size() == 0) {
+            if (!matches.isEmpty() && mismatches.isEmpty()) {
                 for (String match : matches) {
                     if (UrlUtils.isMatchGlobPattern(match, value, param)) {
                         return true;
@@ -240,7 +240,7 @@ public class ConditionRouter implements Router, Comparable<Router> {
                 return false;
             }
 
-            if (mismatches.size() > 0 && matches.size() == 0) {
+            if (!mismatches.isEmpty() && matches.isEmpty()) {
                 for (String mismatch : mismatches) {
                     if (UrlUtils.isMatchGlobPattern(mismatch, value, param)) {
                         return false;
@@ -249,7 +249,7 @@ public class ConditionRouter implements Router, Comparable<Router> {
                 return true;
             }
 
-            if (matches.size() > 0 && mismatches.size() > 0) {
+            if (!matches.isEmpty() && !mismatches.isEmpty()) {
                 //when both mismatches and matches contain the same value, then using mismatches first
                 for (String mismatch : mismatches) {
                     if (UrlUtils.isMatchGlobPattern(mismatch, value, param)) {
diff --git a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/AbstractClusterInvoker.java b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/AbstractClusterInvoker.java
index 999a88939b..bf32bc723d 100644
--- a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/AbstractClusterInvoker.java
+++ b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/AbstractClusterInvoker.java
@@ -99,7 +99,7 @@ public abstract class AbstractClusterInvoker<T> implements Invoker<T> {
      * @throws RpcExceptione
      */
     protected Invoker<T> select(LoadBalance loadbalance, Invocation invocation, List<Invoker<T>> invokers, List<Invoker<T>> selected) throws RpcException {
-        if (invokers == null || invokers.size() == 0)
+        if (invokers == null || invokers.isEmpty())
             return null;
         String methodName = invocation == null ? "" : invocation.getMethodName();
 
@@ -125,12 +125,12 @@ public abstract class AbstractClusterInvoker<T> implements Invoker<T> {
     }
 
     private Invoker<T> doselect(LoadBalance loadbalance, Invocation invocation, List<Invoker<T>> invokers, List<Invoker<T>> selected) throws RpcException {
-        if (invokers == null || invokers.size() == 0)
+        if (invokers == null || invokers.isEmpty())
             return null;
         if (invokers.size() == 1)
             return invokers.get(0);
         // If we only have two invokers, use round-robin instead.
-        if (invokers.size() == 2 && selected != null && selected.size() > 0) {
+        if (invokers.size() == 2 && selected != null && !selected.isEmpty()) {
             return selected.get(0) == invokers.get(0) ? invokers.get(1) : invokers.get(0);
         }
         Invoker<T> invoker = loadbalance.select(invokers, getUrl(), invocation);
@@ -185,7 +185,7 @@ public abstract class AbstractClusterInvoker<T> implements Invoker<T> {
                     }
                 }
             }
-            if (reselectInvokers.size() > 0) {
+            if (!reselectInvokers.isEmpty()) {
                 return loadbalance.select(reselectInvokers, getUrl(), invocation);
             }
         } else { // do not check invoker.isAvailable()
@@ -194,7 +194,7 @@ public abstract class AbstractClusterInvoker<T> implements Invoker<T> {
                     reselectInvokers.add(invoker);
                 }
             }
-            if (reselectInvokers.size() > 0) {
+            if (!reselectInvokers.isEmpty()) {
                 return loadbalance.select(reselectInvokers, getUrl(), invocation);
             }
         }
@@ -208,7 +208,7 @@ public abstract class AbstractClusterInvoker<T> implements Invoker<T> {
                     }
                 }
             }
-            if (reselectInvokers.size() > 0) {
+            if (!reselectInvokers.isEmpty()) {
                 return loadbalance.select(reselectInvokers, getUrl(), invocation);
             }
         }
@@ -222,7 +222,7 @@ public abstract class AbstractClusterInvoker<T> implements Invoker<T> {
         LoadBalance loadbalance;
 
         List<Invoker<T>> invokers = list(invocation);
-        if (invokers != null && invokers.size() > 0) {
+        if (invokers != null && !invokers.isEmpty()) {
             loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(invokers.get(0).getUrl()
                     .getMethodParameter(invocation.getMethodName(), Constants.LOADBALANCE_KEY, Constants.DEFAULT_LOADBALANCE));
         } else {
@@ -247,7 +247,7 @@ public abstract class AbstractClusterInvoker<T> implements Invoker<T> {
     }
 
     protected void checkInvokers(List<Invoker<T>> invokers, Invocation invocation) {
-        if (invokers == null || invokers.size() == 0) {
+        if (invokers == null || invokers.isEmpty()) {
             throw new RpcException("Failed to invoke the method "
                     + invocation.getMethodName() + " in the service " + getInterface().getName()
                     + ". No provider available for the service " + directory.getUrl().getServiceKey()
diff --git a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/MergeableClusterInvoker.java b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/MergeableClusterInvoker.java
index 7893f60570..25868a6d48 100644
--- a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/MergeableClusterInvoker.java
+++ b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/MergeableClusterInvoker.java
@@ -117,7 +117,7 @@ public class MergeableClusterInvoker<T> implements Invoker<T> {
             }
         }
 
-        if (resultList.size() == 0) {
+        if (resultList.isEmpty()) {
             return new RpcResult((Object) null);
         } else if (resultList.size() == 1) {
             return resultList.iterator().next();
diff --git a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/wrapper/MockClusterInvoker.java b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/wrapper/MockClusterInvoker.java
index 76450944ee..0a038c7433 100644
--- a/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/wrapper/MockClusterInvoker.java
+++ b/dubbo-cluster/src/main/java/com/alibaba/dubbo/rpc/cluster/support/wrapper/MockClusterInvoker.java
@@ -98,7 +98,7 @@ public class MockClusterInvoker<T> implements Invoker<T> {
         Invoker<T> minvoker;
 
         List<Invoker<T>> mockInvokers = selectMockInvoker(invocation);
-        if (mockInvokers == null || mockInvokers.size() == 0) {
+        if (mockInvokers == null || mockInvokers.isEmpty()) {
             minvoker = (Invoker<T>) new MockInvoker(directory.getUrl());
         } else {
             minvoker = mockInvokers.get(0);
diff --git a/dubbo-common/src/main/java/com/alibaba/dubbo/common/URL.java b/dubbo-common/src/main/java/com/alibaba/dubbo/common/URL.java
index 744800e185..eb5c144b0d 100644
--- a/dubbo-common/src/main/java/com/alibaba/dubbo/common/URL.java
+++ b/dubbo-common/src/main/java/com/alibaba/dubbo/common/URL.java
@@ -1023,7 +1023,7 @@ public final class URL implements Serializable {
     }
 
     public URL removeParameters(Collection<String> keys) {
-        if (keys == null || keys.size() == 0) {
+        if (keys == null || keys.isEmpty()) {
             return this;
         }
         return removeParameters(keys.toArray(new String[0]));
diff --git a/dubbo-common/src/main/java/com/alibaba/dubbo/common/extension/ExtensionLoader.java b/dubbo-common/src/main/java/com/alibaba/dubbo/common/extension/ExtensionLoader.java
index 5eddd52453..8013571547 100644
--- a/dubbo-common/src/main/java/com/alibaba/dubbo/common/extension/ExtensionLoader.java
+++ b/dubbo-common/src/main/java/com/alibaba/dubbo/common/extension/ExtensionLoader.java
@@ -206,7 +206,7 @@ public class ExtensionLoader<T> {
             if (!name.startsWith(Constants.REMOVE_VALUE_PREFIX)
                     && !names.contains(Constants.REMOVE_VALUE_PREFIX + name)) {
                 if (Constants.DEFAULT_KEY.equals(name)) {
-                    if (usrs.size() > 0) {
+                    if (!usrs.isEmpty()) {
                         exts.addAll(0, usrs);
                         usrs.clear();
                     }
@@ -216,7 +216,7 @@ public class ExtensionLoader<T> {
                 }
             }
         }
-        if (usrs.size() > 0) {
+        if (!usrs.isEmpty()) {
             exts.addAll(usrs);
         }
         return exts;
@@ -495,7 +495,7 @@ public class ExtensionLoader<T> {
             }
             injectExtension(instance);
             Set<Class<?>> wrapperClasses = cachedWrapperClasses;
-            if (wrapperClasses != null && wrapperClasses.size() > 0) {
+            if (wrapperClasses != null && !wrapperClasses.isEmpty()) {
                 for (Class<?> wrapperClass : wrapperClasses) {
                     instance = injectExtension((T) wrapperClass.getConstructor(type).newInstance(instance));
                 }
diff --git a/dubbo-common/src/main/java/com/alibaba/dubbo/common/extension/factory/SpiExtensionFactory.java b/dubbo-common/src/main/java/com/alibaba/dubbo/common/extension/factory/SpiExtensionFactory.java
index 6c098de2d7..0fc857ed50 100644
--- a/dubbo-common/src/main/java/com/alibaba/dubbo/common/extension/factory/SpiExtensionFactory.java
+++ b/dubbo-common/src/main/java/com/alibaba/dubbo/common/extension/factory/SpiExtensionFactory.java
@@ -28,7 +28,7 @@ public class SpiExtensionFactory implements ExtensionFactory {
     public <T> T getExtension(Class<T> type, String name) {
         if (type.isInterface() && type.isAnnotationPresent(SPI.class)) {
             ExtensionLoader<T> loader = ExtensionLoader.getExtensionLoader(type);
-            if (loader.getSupportedExtensions().size() > 0) {
+            if (!loader.getSupportedExtensions().isEmpty()) {
                 return loader.getAdaptiveExtension();
             }
         }
diff --git a/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/CollectionUtils.java b/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/CollectionUtils.java
index cfda8a480f..183c21dd72 100644
--- a/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/CollectionUtils.java
+++ b/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/CollectionUtils.java
@@ -54,7 +54,7 @@ public class CollectionUtils {
 
     @SuppressWarnings({"unchecked", "rawtypes"})
     public static <T> List<T> sort(List<T> list) {
-        if (list != null && list.size() > 0) {
+        if (list != null && !list.isEmpty()) {
             Collections.sort((List) list);
         }
         return list;
@@ -94,7 +94,7 @@ public class CollectionUtils {
             return null;
         }
         Map<String, String> map = new HashMap<String, String>();
-        if (list == null || list.size() == 0) {
+        if (list == null || list.isEmpty()) {
             return map;
         }
         for (String item : list) {
@@ -199,11 +199,11 @@ public class CollectionUtils {
     }
 
     public static boolean isEmpty(Collection<?> collection) {
-        return collection == null || collection.size() == 0;
+        return collection == null || collection.isEmpty();
     }
 
     public static boolean isNotEmpty(Collection<?> collection) {
-        return collection != null && collection.size() > 0;
+        return collection != null && !collection.isEmpty();
     }
 
 }
\ No newline at end of file
diff --git a/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/ConfigUtils.java b/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/ConfigUtils.java
index ff7ab6aac7..ae057a89a5 100644
--- a/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/ConfigUtils.java
+++ b/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/ConfigUtils.java
@@ -244,7 +244,7 @@ public class ConfigUtils {
             logger.warn("Fail to load " + fileName + " file: " + t.getMessage(), t);
         }
 
-        if (list.size() == 0) {
+        if (list.isEmpty()) {
             if (!optional) {
                 logger.warn("No " + fileName + " found on the class path.");
             }
diff --git a/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/UrlUtils.java b/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/UrlUtils.java
index afaa7410f3..9ba130081f 100644
--- a/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/UrlUtils.java
+++ b/dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/UrlUtils.java
@@ -303,7 +303,7 @@ public class UrlUtils {
 
     //compatible for dubbo-2.0.0
     public static List<String> revertForbid(List<String> forbid, Set<URL> subscribed) {
-        if (forbid != null && forbid.size() > 0) {
+        if (forbid != null && !forbid.isEmpty()) {
             List<String> newForbid = new ArrayList<String>();
             for (String serviceName : forbid) {
                 if (!serviceName.contains(":") && !serviceName.contains("/")) {
diff --git a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractInterfaceConfig.java b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractInterfaceConfig.java
index 6fbed0abe3..acb22a4fd0 100644
--- a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractInterfaceConfig.java
+++ b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractInterfaceConfig.java
@@ -104,7 +104,7 @@ public abstract class AbstractInterfaceConfig extends AbstractMethodConfig {
 
     protected void checkRegistry() {
         // for backward compatibility
-        if (registries == null || registries.size() == 0) {
+        if (registries == null || registries.isEmpty()) {
             String address = ConfigUtils.getProperty("dubbo.registry.address");
             if (address != null && address.length() > 0) {
                 registries = new ArrayList<RegistryConfig>();
@@ -116,7 +116,7 @@ public abstract class AbstractInterfaceConfig extends AbstractMethodConfig {
                 }
             }
         }
-        if ((registries == null || registries.size() == 0)) {
+        if ((registries == null || registries.isEmpty())) {
             throw new IllegalStateException((getClass().getSimpleName().startsWith("Reference")
                     ? "No such any registry to refer service in consumer "
                     : "No such any registry to export service in provider ")
@@ -159,7 +159,7 @@ public abstract class AbstractInterfaceConfig extends AbstractMethodConfig {
     protected List<URL> loadRegistries(boolean provider) {
         checkRegistry();
         List<URL> registryList = new ArrayList<URL>();
-        if (registries != null && registries.size() > 0) {
+        if (registries != null && !registries.isEmpty()) {
             for (RegistryConfig config : registries) {
                 String address = config.getAddress();
                 if (address == null || address.length() == 0) {
@@ -257,7 +257,7 @@ public abstract class AbstractInterfaceConfig extends AbstractMethodConfig {
             throw new IllegalStateException("The interface class " + interfaceClass + " is not a interface!");
         }
         // check if methods exist in the interface
-        if (methods != null && methods.size() > 0) {
+        if (methods != null && !methods.isEmpty()) {
             for (MethodConfig methodBean : methods) {
                 String methodName = methodBean.getName();
                 if (methodName == null || methodName.length() == 0) {
@@ -444,7 +444,7 @@ public abstract class AbstractInterfaceConfig extends AbstractMethodConfig {
     }
 
     public RegistryConfig getRegistry() {
-        return registries == null || registries.size() == 0 ? null : registries.get(0);
+        return registries == null || registries.isEmpty() ? null : registries.get(0);
     }
 
     public void setRegistry(RegistryConfig registry) {
diff --git a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractServiceConfig.java b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractServiceConfig.java
index 880d694e1e..00aed9434a 100644
--- a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractServiceConfig.java
+++ b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/AbstractServiceConfig.java
@@ -167,7 +167,7 @@ public abstract class AbstractServiceConfig extends AbstractInterfaceConfig {
     }
 
     public ProtocolConfig getProtocol() {
-        return protocols == null || protocols.size() == 0 ? null : protocols.get(0);
+        return protocols == null || protocols.isEmpty() ? null : protocols.get(0);
     }
 
     public void setProtocol(ProtocolConfig protocol) {
diff --git a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ApplicationConfig.java b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ApplicationConfig.java
index 2fdedb1113..9238a11508 100644
--- a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ApplicationConfig.java
+++ b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ApplicationConfig.java
@@ -151,7 +151,7 @@ public class ApplicationConfig extends AbstractConfig {
     }
 
     public RegistryConfig getRegistry() {
-        return registries == null || registries.size() == 0 ? null : registries.get(0);
+        return registries == null || registries.isEmpty() ? null : registries.get(0);
     }
 
     public void setRegistry(RegistryConfig registry) {
diff --git a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ModuleConfig.java b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ModuleConfig.java
index 720ee5853d..a4e0ee9801 100644
--- a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ModuleConfig.java
+++ b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ModuleConfig.java
@@ -99,7 +99,7 @@ public class ModuleConfig extends AbstractConfig {
     }
 
     public RegistryConfig getRegistry() {
-        return registries == null || registries.size() == 0 ? null : registries.get(0);
+        return registries == null || registries.isEmpty() ? null : registries.get(0);
     }
 
     public void setRegistry(RegistryConfig registry) {
diff --git a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ReferenceConfig.java b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ReferenceConfig.java
index 791feea3d1..1cb58ae28d 100644
--- a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ReferenceConfig.java
+++ b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ReferenceConfig.java
@@ -148,7 +148,7 @@ public class ReferenceConfig<T> extends AbstractReferenceConfig {
     }
 
     public URL toUrl() {
-        return urls == null || urls.size() == 0 ? null : urls.iterator().next();
+        return urls == null || urls.isEmpty() ? null : urls.iterator().next();
     }
 
     public List<URL> toUrls() {
@@ -305,7 +305,7 @@ public class ReferenceConfig<T> extends AbstractReferenceConfig {
         appendParameters(map, consumer, Constants.DEFAULT_KEY);
         appendParameters(map, this);
         String prefix = StringUtils.getServiceKey(map);
-        if (methods != null && methods.size() > 0) {
+        if (methods != null && !methods.isEmpty()) {
             for (MethodConfig method : methods) {
                 appendParameters(map, method, method.getName());
                 String retryKey = method.getName() + ".retry";
@@ -376,7 +376,7 @@ public class ReferenceConfig<T> extends AbstractReferenceConfig {
                 }
             } else { // assemble URL from register center's configuration
                 List<URL> us = loadRegistries(false);
-                if (us != null && us.size() > 0) {
+                if (us != null && !us.isEmpty()) {
                     for (URL u : us) {
                         URL monitorUrl = loadMonitor(u);
                         if (monitorUrl != null) {
@@ -385,7 +385,7 @@ public class ReferenceConfig<T> extends AbstractReferenceConfig {
                         urls.add(u.addParameterAndEncoded(Constants.REFER_KEY, StringUtils.toQueryString(map)));
                     }
                 }
-                if (urls == null || urls.size() == 0) {
+                if (urls == null || urls.isEmpty()) {
                     throw new IllegalStateException("No such any registry to reference " + interfaceName + " on the consumer " + NetUtils.getLocalHost() + " use dubbo version " + Version.getVersion() + ", please config <dubbo:registry address=\"...\" /> to your spring config.");
                 }
             }
diff --git a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ServiceConfig.java b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ServiceConfig.java
index d2e7e9b557..dfb633790a 100644
--- a/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ServiceConfig.java
+++ b/dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ServiceConfig.java
@@ -105,7 +105,7 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
 
     @Deprecated
     private static final List<ProtocolConfig> convertProviderToProtocol(List<ProviderConfig> providers) {
-        if (providers == null || providers.size() == 0) {
+        if (providers == null || providers.isEmpty()) {
             return null;
         }
         List<ProtocolConfig> protocols = new ArrayList<ProtocolConfig>(providers.size());
@@ -117,7 +117,7 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
 
     @Deprecated
     private static final List<ProviderConfig> convertProtocolToProvider(List<ProtocolConfig> protocols) {
-        if (protocols == null || protocols.size() == 0) {
+        if (protocols == null || protocols.isEmpty()) {
             return null;
         }
         List<ProviderConfig> providers = new ArrayList<ProviderConfig>(protocols.size());
@@ -175,7 +175,7 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
     }
 
     public URL toUrl() {
-        return urls == null || urls.size() == 0 ? null : urls.iterator().next();
+        return urls == null || urls.isEmpty() ? null : urls.iterator().next();
     }
 
     public List<URL> toUrls() {
@@ -337,7 +337,7 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
         if (unexported) {
             return;
         }
-        if (exporters != null && exporters.size() > 0) {
+        if (exporters != null && !exporters.isEmpty()) {
             for (Exporter<?> exporter : exporters) {
                 try {
                     exporter.unexport();
@@ -376,7 +376,7 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
         appendParameters(map, provider, Constants.DEFAULT_KEY);
         appendParameters(map, protocolConfig);
         appendParameters(map, this);
-        if (methods != null && methods.size() > 0) {
+        if (methods != null && !methods.isEmpty()) {
             for (MethodConfig method : methods) {
                 appendParameters(map, method, method.getName());
                 String retryKey = method.getName() + ".retry";
@@ -387,7 +387,7 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
                     }
                 }
                 List<ArgumentConfig> arguments = method.getArguments();
-                if (arguments != null && arguments.size() > 0) {
+                if (arguments != null && !arguments.isEmpty()) {
                     for (ArgumentConfig argument : arguments) {
                         // convert argument type
                         if (argument.getType() != null && argument.getType().length() > 0) {
@@ -489,7 +489,7 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
                 if (logger.isInfoEnabled()) {
                     logger.info("Export dubbo service " + interfaceClass.getName() + " to url " + url);
                 }
-                if (registryURLs != null && registryURLs.size() > 0) {
+                if (registryURLs != null && !registryURLs.isEmpty()) {
                     for (URL registryURL : registryURLs) {
                         url = url.addParameterIfAbsent("dynamic", registryURL.getParameter("dynamic"));
                         URL monitorUrl = loadMonitor(registryURL);
@@ -568,7 +568,7 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
                     logger.warn(e.getMessage(), e);
                 }
                 if (isInvalidLocalHost(hostToBind)) {
-                    if (registryURLs != null && registryURLs.size() > 0) {
+                    if (registryURLs != null && !registryURLs.isEmpty()) {
                         for (URL registryURL : registryURLs) {
                             try {
                                 Socket socket = new Socket();
@@ -693,12 +693,12 @@ public class ServiceConfig<T> extends AbstractServiceConfig {
     }
 
     private void checkProtocol() {
-        if ((protocols == null || protocols.size() == 0)
+        if ((protocols == null || protocols.isEmpty())
                 && provider != null) {
             setProtocols(provider.getProtocols());
         }
         // backward compatibility
-        if (protocols == null || protocols.size() == 0) {
+        if (protocols == null || protocols.isEmpty()) {
             setProtocol(new ProtocolConfig());
         }
         for (ProtocolConfig protocolConfig : protocols) {
diff --git a/dubbo-config/dubbo-config-spring/src/main/java/com/alibaba/dubbo/config/spring/ReferenceBean.java b/dubbo-config/dubbo-config-spring/src/main/java/com/alibaba/dubbo/config/spring/ReferenceBean.java
index b4d9986fd0..f3aa9b0249 100644
--- a/dubbo-config/dubbo-config-spring/src/main/java/com/alibaba/dubbo/config/spring/ReferenceBean.java
+++ b/dubbo-config/dubbo-config-spring/src/main/java/com/alibaba/dubbo/config/spring/ReferenceBean.java
@@ -129,9 +129,9 @@ public class ReferenceBean<T> extends ReferenceConfig<T> implements FactoryBean,
                 }
             }
         }
-        if ((getRegistries() == null || getRegistries().size() == 0)
-                && (getConsumer() == null || getConsumer().getRegistries() == null || getConsumer().getRegistries().size() == 0)
-                && (getApplication() == null || getApplication().getRegistries() == null || getApplication().getRegistries().size() == 0)) {
+        if ((getRegistries() == null || getRegistries().isEmpty())
+                && (getConsumer() == null || getConsumer().getRegistries() == null || getConsumer().getRegistries().isEmpty())
+                && (getApplication() == null || getApplication().getRegistries() == null || getApplication().getRegistries().isEmpty())) {
             Map<String, RegistryConfig> registryConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, RegistryConfig.class, false, false);
             if (registryConfigMap != null && registryConfigMap.size() > 0) {
                 List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
@@ -140,7 +140,7 @@ public class ReferenceBean<T> extends ReferenceConfig<T> implements FactoryBean,
                         registryConfigs.add(config);
                     }
                 }
-                if (registryConfigs != null && registryConfigs.size() > 0) {
+                if (registryConfigs != null && !registryConfigs.isEmpty()) {
                     super.setRegistries(registryConfigs);
                 }
             }
diff --git a/dubbo-config/dubbo-config-spring/src/main/java/com/alibaba/dubbo/config/spring/ServiceBean.java b/dubbo-config/dubbo-config-spring/src/main/java/com/alibaba/dubbo/config/spring/ServiceBean.java
index 1ee6c452b2..2e614efdb6 100644
--- a/dubbo-config/dubbo-config-spring/src/main/java/com/alibaba/dubbo/config/spring/ServiceBean.java
+++ b/dubbo-config/dubbo-config-spring/src/main/java/com/alibaba/dubbo/config/spring/ServiceBean.java
@@ -145,7 +145,7 @@ public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean
                             providerConfigs.add(config);
                         }
                     }
-                    if (providerConfigs.size() > 0) {
+                    if (!providerConfigs.isEmpty()) {
                         setProviders(providerConfigs);
                     }
                 } else {
@@ -200,9 +200,9 @@ public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean
                 }
             }
         }
-        if ((getRegistries() == null || getRegistries().size() == 0)
-                && (getProvider() == null || getProvider().getRegistries() == null || getProvider().getRegistries().size() == 0)
-                && (getApplication() == null || getApplication().getRegistries() == null || getApplication().getRegistries().size() == 0)) {
+        if ((getRegistries() == null || getRegistries().isEmpty())
+                && (getProvider() == null || getProvider().getRegistries() == null || getProvider().getRegistries().isEmpty())
+                && (getApplication() == null || getApplication().getRegistries() == null || getApplication().getRegistries().isEmpty())) {
             Map<String, RegistryConfig> registryConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, RegistryConfig.class, false, false);
             if (registryConfigMap != null && registryConfigMap.size() > 0) {
                 List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
@@ -211,7 +211,7 @@ public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean
                         registryConfigs.add(config);
                     }
                 }
-                if (registryConfigs != null && registryConfigs.size() > 0) {
+                if (registryConfigs != null && !registryConfigs.isEmpty()) {
                     super.setRegistries(registryConfigs);
                 }
             }
@@ -235,8 +235,8 @@ public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean
                 }
             }
         }
-        if ((getProtocols() == null || getProtocols().size() == 0)
-                && (getProvider() == null || getProvider().getProtocols() == null || getProvider().getProtocols().size() == 0)) {
+        if ((getProtocols() == null || getProtocols().isEmpty())
+                && (getProvider() == null || getProvider().getProtocols() == null || getProvider().getProtocols().isEmpty())) {
             Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
             if (protocolConfigMap != null && protocolConfigMap.size() > 0) {
                 List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>();
@@ -245,7 +245,7 @@ public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean
                         protocolConfigs.add(config);
                     }
                 }
-                if (protocolConfigs != null && protocolConfigs.size() > 0) {
+                if (protocolConfigs != null && !protocolConfigs.isEmpty()) {
                     super.setProtocols(protocolConfigs);
                 }
             }
diff --git a/dubbo-filter/dubbo-filter-validation/src/main/java/com/alibaba/dubbo/validation/support/jvalidation/JValidator.java b/dubbo-filter/dubbo-filter-validation/src/main/java/com/alibaba/dubbo/validation/support/jvalidation/JValidator.java
index f87624865a..9010d37260 100644
--- a/dubbo-filter/dubbo-filter-validation/src/main/java/com/alibaba/dubbo/validation/support/jvalidation/JValidator.java
+++ b/dubbo-filter/dubbo-filter-validation/src/main/java/com/alibaba/dubbo/validation/support/jvalidation/JValidator.java
@@ -265,7 +265,7 @@ public class JValidator implements Validator {
             validate(violations, arg, classgroups);
         }
 
-        if (violations.size() > 0) {
+        if (!violations.isEmpty()) {
             logger.error("Failed to validate service: " + clazz.getName() + ", method: " + methodName + ", cause: " + violations);
             throw new ConstraintViolationException("Failed to validate service: " + clazz.getName() + ", method: " + methodName + ", cause: " + violations, violations);
         }
diff --git a/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/integration/RegistryDirectory.java b/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/integration/RegistryDirectory.java
index 5a03636ffc..ee37c85c95 100644
--- a/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/integration/RegistryDirectory.java
+++ b/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/integration/RegistryDirectory.java
@@ -123,7 +123,7 @@ public class RegistryDirectory<T> extends AbstractDirectory<T> implements Notify
      * @return
      */
     public static List<Configurator> toConfigurators(List<URL> urls) {
-        if (urls == null || urls.size() == 0) {
+        if (urls == null || urls.isEmpty()) {
             return Collections.emptyList();
         }
 
@@ -199,11 +199,11 @@ public class RegistryDirectory<T> extends AbstractDirectory<T> implements Notify
             }
         }
         // configurators
-        if (configuratorUrls != null && configuratorUrls.size() > 0) {
+        if (configuratorUrls != null && !configuratorUrls.isEmpty()) {
             this.configurators = toConfigurators(configuratorUrls);
         }
         // routers
-        if (routerUrls != null && routerUrls.size() > 0) {
+        if (routerUrls != null && !routerUrls.isEmpty()) {
             List<Router> routers = toRouters(routerUrls);
             if (routers != null) { // null - do nothing
                 setRouters(routers);
@@ -212,7 +212,7 @@ public class RegistryDirectory<T> extends AbstractDirectory<T> implements Notify
         List<Configurator> localConfigurators = this.configurators; // local reference
         // merge override parameters
         this.overrideDirectoryUrl = directoryUrl;
-        if (localConfigurators != null && localConfigurators.size() > 0) {
+        if (localConfigurators != null && !localConfigurators.isEmpty()) {
             for (Configurator configurator : localConfigurators) {
                 this.overrideDirectoryUrl = configurator.configure(overrideDirectoryUrl);
             }
@@ -239,13 +239,13 @@ public class RegistryDirectory<T> extends AbstractDirectory<T> implements Notify
         } else {
             this.forbidden = false; // Allow to access
             Map<String, Invoker<T>> oldUrlInvokerMap = this.urlInvokerMap; // local reference
-            if (invokerUrls.size() == 0 && this.cachedInvokerUrls != null) {
+            if (invokerUrls.isEmpty() && this.cachedInvokerUrls != null) {
                 invokerUrls.addAll(this.cachedInvokerUrls);
             } else {
                 this.cachedInvokerUrls = new HashSet<URL>();
                 this.cachedInvokerUrls.addAll(invokerUrls);//Cached invoker urls, convenient for comparison
             }
-            if (invokerUrls.size() == 0) {
+            if (invokerUrls.isEmpty()) {
                 return;
             }
             Map<String, Invoker<T>> newUrlInvokerMap = toInvokers(invokerUrls);// Translate url list to Invoker map
@@ -303,10 +303,10 @@ public class RegistryDirectory<T> extends AbstractDirectory<T> implements Notify
      */
     private List<Router> toRouters(List<URL> urls) {
         List<Router> routers = new ArrayList<Router>();
-        if (urls == null || urls.size() < 1) {
+        if (urls == null || urls.isEmpty()) {
             return routers;
         }
-        if (urls != null && urls.size() > 0) {
+        if (urls != null && !urls.isEmpty()) {
             for (URL url : urls) {
                 if (Constants.EMPTY_PROTOCOL.equals(url.getProtocol())) {
                     continue;
@@ -335,7 +335,7 @@ public class RegistryDirectory<T> extends AbstractDirectory<T> implements Notify
      */
     private Map<String, Invoker<T>> toInvokers(List<URL> urls) {
         Map<String, Invoker<T>> newUrlInvokerMap = new HashMap<String, Invoker<T>>();
-        if (urls == null || urls.size() == 0) {
+        if (urls == null || urls.isEmpty()) {
             return newUrlInvokerMap;
         }
         Set<String> keys = new HashSet<String>();
@@ -408,7 +408,7 @@ public class RegistryDirectory<T> extends AbstractDirectory<T> implements Notify
         providerUrl = ClusterUtils.mergeUrl(providerUrl, queryMap); // Merge the consumer side parameters
 
         List<Configurator> localConfigurators = this.configurators; // local reference
-        if (localConfigurators != null && localConfigurators.size() > 0) {
+        if (localConfigurators != null && !localConfigurators.isEmpty()) {
             for (Configurator configurator : localConfigurators) {
                 providerUrl = configurator.configure(providerUrl);
             }
@@ -488,7 +488,7 @@ public class RegistryDirectory<T> extends AbstractDirectory<T> implements Notify
         if (serviceMethods != null && serviceMethods.length > 0) {
             for (String method : serviceMethods) {
                 List<Invoker<T>> methodInvokers = newMethodInvokerMap.get(method);
-                if (methodInvokers == null || methodInvokers.size() == 0) {
+                if (methodInvokers == null || methodInvokers.isEmpty()) {
                     methodInvokers = newInvokersList;
                 }
                 newMethodInvokerMap.put(method, route(methodInvokers, method));
diff --git a/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/status/RegistryStatusChecker.java b/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/status/RegistryStatusChecker.java
index 3436d7c711..998d6cfabd 100644
--- a/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/status/RegistryStatusChecker.java
+++ b/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/status/RegistryStatusChecker.java
@@ -33,7 +33,7 @@ public class RegistryStatusChecker implements StatusChecker {
 
     public Status check() {
         Collection<Registry> regsitries = AbstractRegistryFactory.getRegistries();
-        if (regsitries == null || regsitries.size() == 0) {
+        if (regsitries == null || regsitries.isEmpty()) {
             return new Status(Status.Level.UNKNOWN);
         }
         Status.Level level = Status.Level.OK;
diff --git a/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/support/AbstractRegistry.java b/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/support/AbstractRegistry.java
index 1ec2da435d..55e2455c84 100644
--- a/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/support/AbstractRegistry.java
+++ b/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/support/AbstractRegistry.java
@@ -98,7 +98,7 @@ public abstract class AbstractRegistry implements Registry {
     }
 
     protected static List<URL> filterEmpty(URL url, List<URL> urls) {
-        if (urls == null || urls.size() == 0) {
+        if (urls == null || urls.isEmpty()) {
             List<URL> result = new ArrayList<URL>(1);
             result.add(url.setProtocol(Constants.EMPTY_PROTOCOL));
             return result;
@@ -253,7 +253,7 @@ public abstract class AbstractRegistry implements Registry {
             };
             subscribe(url, listener); // Subscribe logic guarantees the first notify to return
             List<URL> urls = reference.get();
-            if (urls != null && urls.size() > 0) {
+            if (urls != null && !urls.isEmpty()) {
                 for (URL u : urls) {
                     if (!Constants.EMPTY_PROTOCOL.equals(u.getProtocol())) {
                         result.add(u);
@@ -374,7 +374,7 @@ public abstract class AbstractRegistry implements Registry {
         if (listener == null) {
             throw new IllegalArgumentException("notify listener == null");
         }
-        if ((urls == null || urls.size() == 0)
+        if ((urls == null || urls.isEmpty())
                 && !Constants.ANY_VALUE.equals(url.getServiceInterface())) {
             logger.warn("Ignore empty notify urls for subscribe url " + url);
             return;
diff --git a/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/support/FailbackRegistry.java b/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/support/FailbackRegistry.java
index a0ea25174b..207fd49c4d 100644
--- a/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/support/FailbackRegistry.java
+++ b/dubbo-registry/dubbo-registry-api/src/main/java/com/alibaba/dubbo/registry/support/FailbackRegistry.java
@@ -203,7 +203,7 @@ public abstract class FailbackRegistry extends AbstractRegistry {
             Throwable t = e;
 
             List<URL> urls = getCacheUrls(url);
-            if (urls != null && urls.size() > 0) {
+            if (urls != null && !urls.isEmpty()) {
                 notify(url, listener, urls);
                 logger.error("Failed to subscribe " + url + ", Using cached list: " + urls + " from cache file: " + getUrl().getParameter(Constants.FILE_KEY, System.getProperty("user.home") + "/dubbo-registry-" + url.getHost() + ".cache") + ", cause: " + t.getMessage(), t);
             } else {
@@ -339,7 +339,7 @@ public abstract class FailbackRegistry extends AbstractRegistry {
         }
         if (!failedUnregistered.isEmpty()) {
             Set<URL> failed = new HashSet<URL>(failedUnregistered);
-            if (failed.size() > 0) {
+            if (!failed.isEmpty()) {
                 if (logger.isInfoEnabled()) {
                     logger.info("Retry unregister " + failed);
                 }
@@ -389,7 +389,7 @@ public abstract class FailbackRegistry extends AbstractRegistry {
         if (!failedUnsubscribed.isEmpty()) {
             Map<URL, Set<NotifyListener>> failed = new HashMap<URL, Set<NotifyListener>>(failedUnsubscribed);
             for (Map.Entry<URL, Set<NotifyListener>> entry : new HashMap<URL, Set<NotifyListener>>(failed).entrySet()) {
-                if (entry.getValue() == null || entry.getValue().size() == 0) {
+                if (entry.getValue() == null || entry.getValue().isEmpty()) {
                     failed.remove(entry.getKey());
                 }
             }
diff --git a/dubbo-registry/dubbo-registry-multicast/src/main/java/com/alibaba/dubbo/registry/multicast/MulticastRegistry.java b/dubbo-registry/dubbo-registry-multicast/src/main/java/com/alibaba/dubbo/registry/multicast/MulticastRegistry.java
index d96cc42a93..11613f834e 100644
--- a/dubbo-registry/dubbo-registry-multicast/src/main/java/com/alibaba/dubbo/registry/multicast/MulticastRegistry.java
+++ b/dubbo-registry/dubbo-registry-multicast/src/main/java/com/alibaba/dubbo/registry/multicast/MulticastRegistry.java
@@ -210,7 +210,7 @@ public class MulticastRegistry extends FailbackRegistry {
         } else if (msg.startsWith(Constants.SUBSCRIBE)) {
             URL url = URL.valueOf(msg.substring(Constants.SUBSCRIBE.length()).trim());
             Set<URL> urls = getRegistered();
-            if (urls != null && urls.size() > 0) {
+            if (urls != null && !urls.isEmpty()) {
                 for (URL u : urls) {
                     if (UrlUtils.isMatch(url, u)) {
                         String host = remoteAddress != null && remoteAddress.getAddress() != null
@@ -359,7 +359,7 @@ public class MulticastRegistry extends FailbackRegistry {
 
     private List<URL> toList(Set<URL> urls) {
         List<URL> list = new ArrayList<URL>();
-        if (urls != null && urls.size() > 0) {
+        if (urls != null && !urls.isEmpty()) {
             for (URL url : urls) {
                 list.add(url);
             }
@@ -395,13 +395,13 @@ public class MulticastRegistry extends FailbackRegistry {
                 urls.addAll(values);
             }
         }
-        if (urls == null || urls.size() == 0) {
+        if (urls == null || urls.isEmpty()) {
             List<URL> cacheUrls = getCacheUrls(url);
-            if (cacheUrls != null && cacheUrls.size() > 0) {
+            if (cacheUrls != null && !cacheUrls.isEmpty()) {
                 urls.addAll(cacheUrls);
             }
         }
-        if (urls == null || urls.size() == 0) {
+        if (urls == null || urls.isEmpty()) {
             for (URL u : getRegistered()) {
                 if (UrlUtils.isMatch(url, u)) {
                     urls.add(u);
diff --git a/dubbo-registry/dubbo-registry-redis/src/main/java/com/alibaba/dubbo/registry/redis/RedisRegistry.java b/dubbo-registry/dubbo-registry-redis/src/main/java/com/alibaba/dubbo/registry/redis/RedisRegistry.java
index 6ce58db5f2..617798c597 100644
--- a/dubbo-registry/dubbo-registry-redis/src/main/java/com/alibaba/dubbo/registry/redis/RedisRegistry.java
+++ b/dubbo-registry/dubbo-registry-redis/src/main/java/com/alibaba/dubbo/registry/redis/RedisRegistry.java
@@ -194,7 +194,7 @@ public class RedisRegistry extends FailbackRegistry {
     // The monitoring center is responsible for deleting outdated dirty data
     private void clean(Jedis jedis) {
         Set<String> keys = jedis.keys(root + Constants.ANY_VALUE);
-        if (keys != null && keys.size() > 0) {
+        if (keys != null && !keys.isEmpty()) {
             for (String key : keys) {
                 Map<String, String> values = jedis.hgetAll(key);
                 if (values != null && values.size() > 0) {
@@ -352,7 +352,7 @@ public class RedisRegistry extends FailbackRegistry {
                     if (service.endsWith(Constants.ANY_VALUE)) {
                         admin = true;
                         Set<String> keys = jedis.keys(service);
-                        if (keys != null && keys.size() > 0) {
+                        if (keys != null && !keys.isEmpty()) {
                             Map<String, Set<String>> serviceKeys = new HashMap<String, Set<String>>();
                             for (String key : keys) {
                                 String serviceKey = toServicePath(key);
@@ -399,8 +399,8 @@ public class RedisRegistry extends FailbackRegistry {
     }
 
     private void doNotify(Jedis jedis, Collection<String> keys, URL url, Collection<NotifyListener> listeners) {
-        if (keys == null || keys.size() == 0
-                || listeners == null || listeners.size() == 0) {
+        if (keys == null || keys.isEmpty()
+                || listeners == null || listeners.isEmpty()) {
             return;
         }
         long now = System.currentTimeMillis();
@@ -442,7 +442,7 @@ public class RedisRegistry extends FailbackRegistry {
                 logger.info("redis notify: " + key + " = " + urls);
             }
         }
-        if (result == null || result.size() == 0) {
+        if (result == null || result.isEmpty()) {
             return;
         }
         for (NotifyListener listener : listeners) {
@@ -584,7 +584,7 @@ public class RedisRegistry extends FailbackRegistry {
                                             if (!first) {
                                                 first = false;
                                                 Set<String> keys = jedis.keys(service);
-                                                if (keys != null && keys.size() > 0) {
+                                                if (keys != null && !keys.isEmpty()) {
                                                     for (String s : keys) {
                                                         doNotify(jedis, s);
                                                     }
diff --git a/dubbo-registry/dubbo-registry-zookeeper/src/main/java/com/alibaba/dubbo/registry/zookeeper/ZookeeperRegistry.java b/dubbo-registry/dubbo-registry-zookeeper/src/main/java/com/alibaba/dubbo/registry/zookeeper/ZookeeperRegistry.java
index d9747ab814..dcce7e4d49 100644
--- a/dubbo-registry/dubbo-registry-zookeeper/src/main/java/com/alibaba/dubbo/registry/zookeeper/ZookeeperRegistry.java
+++ b/dubbo-registry/dubbo-registry-zookeeper/src/main/java/com/alibaba/dubbo/registry/zookeeper/ZookeeperRegistry.java
@@ -148,7 +148,7 @@ public class ZookeeperRegistry extends FailbackRegistry {
                 }
                 zkClient.create(root, false);
                 List<String> services = zkClient.addChildListener(root, zkListener);
-                if (services != null && services.size() > 0) {
+                if (services != null && !services.isEmpty()) {
                     for (String service : services) {
                         service = URL.decode(service);
                         anyServices.add(service);
@@ -258,7 +258,7 @@ public class ZookeeperRegistry extends FailbackRegistry {
 
     private List<URL> toUrlsWithoutEmpty(URL consumer, List<String> providers) {
         List<URL> urls = new ArrayList<URL>();
-        if (providers != null && providers.size() > 0) {
+        if (providers != null && !providers.isEmpty()) {
             for (String provider : providers) {
                 provider = URL.decode(provider);
                 if (provider.contains("://")) {
diff --git a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/exchange/support/header/HeaderExchangeServer.java b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/exchange/support/header/HeaderExchangeServer.java
index 4410468037..6d77a1822a 100644
--- a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/exchange/support/header/HeaderExchangeServer.java
+++ b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/exchange/support/header/HeaderExchangeServer.java
@@ -154,7 +154,7 @@ public class HeaderExchangeServer implements ExchangeServer {
     public Collection<ExchangeChannel> getExchangeChannels() {
         Collection<ExchangeChannel> exchangeChannels = new ArrayList<ExchangeChannel>();
         Collection<Channel> channels = server.getChannels();
-        if (channels != null && channels.size() > 0) {
+        if (channels != null && !channels.isEmpty()) {
             for (Channel channel : channels) {
                 exchangeChannels.add(HeaderExchangeChannel.getOrAddChannel(channel));
             }
diff --git a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/codec/TelnetCodec.java b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/codec/TelnetCodec.java
index d1f57f24ba..37fbe700a2 100644
--- a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/codec/TelnetCodec.java
+++ b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/codec/TelnetCodec.java
@@ -189,7 +189,7 @@ public class TelnetCodec extends TransportCodec {
         boolean down = endsWith(message, DOWN);
         if (up || down) {
             LinkedList<String> history = (LinkedList<String>) channel.getAttribute(HISTORY_LIST_KEY);
-            if (history == null || history.size() == 0) {
+            if (history == null || history.isEmpty()) {
                 return DecodeResult.NEED_MORE_INPUT;
             }
             Integer index = (Integer) channel.getAttribute(HISTORY_INDEX_KEY);
@@ -256,7 +256,7 @@ public class TelnetCodec extends TransportCodec {
         LinkedList<String> history = (LinkedList<String>) channel.getAttribute(HISTORY_LIST_KEY);
         Integer index = (Integer) channel.getAttribute(HISTORY_INDEX_KEY);
         channel.removeAttribute(HISTORY_INDEX_KEY);
-        if (history != null && history.size() > 0 && index != null && index >= 0 && index < history.size()) {
+        if (history != null && !history.isEmpty() && index != null && index >= 0 && index < history.size()) {
             String value = history.get(index);
             if (value != null) {
                 byte[] b1 = value.getBytes();
@@ -276,7 +276,7 @@ public class TelnetCodec extends TransportCodec {
                 history = new LinkedList<String>();
                 channel.setAttribute(HISTORY_LIST_KEY, history);
             }
-            if (history.size() == 0) {
+            if (history.isEmpty()) {
                 history.addLast(result);
             } else if (!result.equals(history.getLast())) {
                 history.remove(result);
diff --git a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/support/command/HelpTelnetHandler.java b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/support/command/HelpTelnetHandler.java
index 6f36956b12..15bd4d408b 100644
--- a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/support/command/HelpTelnetHandler.java
+++ b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/support/command/HelpTelnetHandler.java
@@ -53,7 +53,7 @@ public class HelpTelnetHandler implements TelnetHandler {
         } else {
             List<List<String>> table = new ArrayList<List<String>>();
             List<TelnetHandler> handlers = extensionLoader.getActivateExtension(channel.getUrl(), "telnet");
-            if (handlers != null && handlers.size() > 0) {
+            if (handlers != null && !handlers.isEmpty()) {
                 for (TelnetHandler handler : handlers) {
                     Help help = handler.getClass().getAnnotation(Help.class);
                     List<String> row = new ArrayList<String>();
diff --git a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/support/command/StatusTelnetHandler.java b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/support/command/StatusTelnetHandler.java
index eaa8d7abf0..a78ae65c40 100644
--- a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/support/command/StatusTelnetHandler.java
+++ b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/telnet/support/command/StatusTelnetHandler.java
@@ -47,7 +47,7 @@ public class StatusTelnetHandler implements TelnetHandler {
             String[] header = new String[]{"resource", "status", "message"};
             List<List<String>> table = new ArrayList<List<String>>();
             Map<String, Status> statuses = new HashMap<String, Status>();
-            if (checkers != null && checkers.size() > 0) {
+            if (checkers != null && !checkers.isEmpty()) {
                 for (StatusChecker checker : checkers) {
                     String name = extensionLoader.getExtensionName(checker);
                     Status stat;
diff --git a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/AbstractServer.java b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/AbstractServer.java
index 199590138c..d0b4842dc8 100644
--- a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/AbstractServer.java
+++ b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/AbstractServer.java
@@ -196,7 +196,7 @@ public abstract class AbstractServer extends AbstractEndpoint implements Server
     @Override
     public void disconnected(Channel ch) throws RemotingException {
         Collection<Channel> channels = getChannels();
-        if (channels.size() == 0) {
+        if (channels.isEmpty()) {
             logger.warn("All clients has discontected from " + ch.getLocalAddress() + ". You can graceful shutdown now.");
         }
         super.disconnected(ch);
diff --git a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/ChannelHandlerDispatcher.java b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/ChannelHandlerDispatcher.java
index f89266ff3e..6a2d9817c9 100644
--- a/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/ChannelHandlerDispatcher.java
+++ b/dubbo-remoting/dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/ChannelHandlerDispatcher.java
@@ -42,7 +42,7 @@ public class ChannelHandlerDispatcher implements ChannelHandler {
     }
 
     public ChannelHandlerDispatcher(Collection<ChannelHandler> handlers) {
-        if (handlers != null && handlers.size() > 0) {
+        if (handlers != null && !handlers.isEmpty()) {
             this.channelHandlers.addAll(handlers);
         }
     }
diff --git a/dubbo-remoting/dubbo-remoting-netty/src/main/java/com/alibaba/dubbo/remoting/transport/netty/NettyServer.java b/dubbo-remoting/dubbo-remoting-netty/src/main/java/com/alibaba/dubbo/remoting/transport/netty/NettyServer.java
index d08ff257f2..c7e77d7e6f 100644
--- a/dubbo-remoting/dubbo-remoting-netty/src/main/java/com/alibaba/dubbo/remoting/transport/netty/NettyServer.java
+++ b/dubbo-remoting/dubbo-remoting-netty/src/main/java/com/alibaba/dubbo/remoting/transport/netty/NettyServer.java
@@ -104,7 +104,7 @@ public class NettyServer extends AbstractServer implements Server {
         }
         try {
             Collection<com.alibaba.dubbo.remoting.Channel> channels = getChannels();
-            if (channels != null && channels.size() > 0) {
+            if (channels != null && !channels.isEmpty()) {
                 for (com.alibaba.dubbo.remoting.Channel channel : channels) {
                     try {
                         channel.close();
diff --git a/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/RpcContext.java b/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/RpcContext.java
index b2993b44bd..e7ecebb2e7 100644
--- a/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/RpcContext.java
+++ b/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/RpcContext.java
@@ -557,7 +557,7 @@ public class RpcContext {
 
     public RpcContext setInvokers(List<Invoker<?>> invokers) {
         this.invokers = invokers;
-        if (invokers != null && invokers.size() > 0) {
+        if (invokers != null && !invokers.isEmpty()) {
             List<URL> urls = new ArrayList<URL>(invokers.size());
             for (Invoker<?> invoker : invokers) {
                 urls.add(invoker.getUrl());
diff --git a/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/listener/ListenerExporterWrapper.java b/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/listener/ListenerExporterWrapper.java
index 5586f2b7c4..bd8f1e56c3 100644
--- a/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/listener/ListenerExporterWrapper.java
+++ b/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/listener/ListenerExporterWrapper.java
@@ -41,7 +41,7 @@ public class ListenerExporterWrapper<T> implements Exporter<T> {
         }
         this.exporter = exporter;
         this.listeners = listeners;
-        if (listeners != null && listeners.size() > 0) {
+        if (listeners != null && !listeners.isEmpty()) {
             RuntimeException exception = null;
             for (ExporterListener listener : listeners) {
                 if (listener != null) {
@@ -67,7 +67,7 @@ public class ListenerExporterWrapper<T> implements Exporter<T> {
         try {
             exporter.unexport();
         } finally {
-            if (listeners != null && listeners.size() > 0) {
+            if (listeners != null && !listeners.isEmpty()) {
                 RuntimeException exception = null;
                 for (ExporterListener listener : listeners) {
                     if (listener != null) {
diff --git a/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/listener/ListenerInvokerWrapper.java b/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/listener/ListenerInvokerWrapper.java
index 4dc3b24ae5..6c7785ce0c 100644
--- a/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/listener/ListenerInvokerWrapper.java
+++ b/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/listener/ListenerInvokerWrapper.java
@@ -44,7 +44,7 @@ public class ListenerInvokerWrapper<T> implements Invoker<T> {
         }
         this.invoker = invoker;
         this.listeners = listeners;
-        if (listeners != null && listeners.size() > 0) {
+        if (listeners != null && !listeners.isEmpty()) {
             for (InvokerListener listener : listeners) {
                 if (listener != null) {
                     try {
@@ -82,7 +82,7 @@ public class ListenerInvokerWrapper<T> implements Invoker<T> {
         try {
             invoker.destroy();
         } finally {
-            if (listeners != null && listeners.size() > 0) {
+            if (listeners != null && !listeners.isEmpty()) {
                 for (InvokerListener listener : listeners) {
                     if (listener != null) {
                         try {
diff --git a/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/protocol/ProtocolFilterWrapper.java b/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/protocol/ProtocolFilterWrapper.java
index 66ec05adad..77653eef2e 100644
--- a/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/protocol/ProtocolFilterWrapper.java
+++ b/dubbo-rpc/dubbo-rpc-api/src/main/java/com/alibaba/dubbo/rpc/protocol/ProtocolFilterWrapper.java
@@ -46,7 +46,7 @@ public class ProtocolFilterWrapper implements Protocol {
     private static <T> Invoker<T> buildInvokerChain(final Invoker<T> invoker, String key, String group) {
         Invoker<T> last = invoker;
         List<Filter> filters = ExtensionLoader.getExtensionLoader(Filter.class).getActivateExtension(invoker.getUrl(), key, group);
-        if (filters.size() > 0) {
+        if (!filters.isEmpty()) {
             for (int i = filters.size() - 1; i >= 0; i--) {
                 final Filter filter = filters.get(i);
                 final Invoker<T> next = last;
diff --git a/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/filter/TraceFilter.java b/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/filter/TraceFilter.java
index 3924ad9422..043ff034ba 100644
--- a/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/filter/TraceFilter.java
+++ b/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/filter/TraceFilter.java
@@ -79,11 +79,11 @@ public class TraceFilter implements Filter {
         if (tracers.size() > 0) {
             String key = invoker.getInterface().getName() + "." + invocation.getMethodName();
             Set<Channel> channels = tracers.get(key);
-            if (channels == null || channels.size() == 0) {
+            if (channels == null || channels.isEmpty()) {
                 key = invoker.getInterface().getName();
                 channels = tracers.get(key);
             }
-            if (channels != null && channels.size() > 0) {
+            if (channels != null && !channels.isEmpty()) {
                 for (Channel channel : new ArrayList<Channel>(channels)) {
                     if (channel.isConnected()) {
                         try {
diff --git a/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/status/ServerStatusChecker.java b/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/status/ServerStatusChecker.java
index 00f47ad7ff..90d552e8c9 100644
--- a/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/status/ServerStatusChecker.java
+++ b/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/status/ServerStatusChecker.java
@@ -32,7 +32,7 @@ public class ServerStatusChecker implements StatusChecker {
 
     public Status check() {
         Collection<ExchangeServer> servers = DubboProtocol.getDubboProtocol().getServers();
-        if (servers == null || servers.size() == 0) {
+        if (servers == null || servers.isEmpty()) {
             return new Status(Status.Level.UNKNOWN);
         }
         Status.Level level = Status.Level.OK;