* Refactor: string checks with idiomatic alternatives

apollo-client/src/main/java/com/ctrip/framework/apollo/internals/RemoteConfigLongPollService.java

@@ -346,7 +346,7 @@ private ServiceDTO resolveConfigService() {
 
   private List<ServiceDTO> getConfigServices() {
     List<ServiceDTO> services = m_serviceLocator.getConfigServices();
-    if (services.size() == 0) {
+    if (services.isEmpty()) {
       throw new ApolloConfigException("No available config service");
     }
 

apollo-client/src/main/java/com/ctrip/framework/apollo/internals/RemoteConfigRepository.java

@@ -379,7 +379,7 @@ public void run() {
 
   private List<ServiceDTO> getConfigServices() {
     List<ServiceDTO> services = m_serviceLocator.getConfigServices();
-    if (services.size() == 0) {
+    if (services.isEmpty()) {
       throw new ApolloConfigException("No available config service");
     }
 

apollo-client/src/main/java/com/ctrip/framework/apollo/util/http/DefaultHttpClient.java

@@ -97,7 +97,7 @@ private <T> HttpResponse<T> doGetWithSerializeFunction(HttpRequest httpRequest,
       conn.setRequestMethod("GET");
 
       Map<String, String> headers = httpRequest.getHeaders();
-      if (headers != null && headers.size() > 0) {
+      if (headers != null && !headers.isEmpty()) {
         for (Map.Entry<String, String> entry : headers.entrySet()) {
           conn.setRequestProperty(entry.getKey(), entry.getValue());
         }

apollo-client/src/main/java/com/ctrip/framework/apollo/util/yaml/YamlParser.java

@@ -73,15 +73,15 @@ private Yaml createYaml() {
   private boolean process(MatchCallback callback, Yaml yaml, String content) {
     int count = 0;
     if (logger.isDebugEnabled()) {
-      logger.debug("Loading from YAML: " + content);
+      logger.debug("Loading from YAML: {}", content);
     }
     for (Object object : yaml.loadAll(content)) {
       if (object != null && process(asMap(object), callback)) {
         count++;
       }
     }
     if (logger.isDebugEnabled()) {
-      logger.debug("Loaded " + count + " document" + (count > 1 ? "s" : "") + " from YAML resource: " + content);
+      logger.debug("Loaded {} document{} from YAML resource: {}", count, count > 1 ? "s" : "", content);
     }
     return (count > 0);
   }
@@ -118,7 +118,7 @@ private boolean process(Map<String, Object> map, MatchCallback callback) {
     properties.putAll(getFlattenedMap(map));
 
     if (logger.isDebugEnabled()) {
-      logger.debug("Merging document (no matchers set): " + map);
+      logger.debug("Merging document (no matchers set): {}", map);
     }
     callback.process(properties, map);
     return true;

apollo-core/src/main/java/com/ctrip/framework/apollo/core/MetaDomainConsts.java

@@ -222,9 +222,7 @@ public void run() {
             updateMetaServerAddresses(metaServerAddresses);
           }
         } catch (Throwable ex) {
-          logger
-              .warn(String.format("Refreshing meta server address failed, will retry in %d seconds",
-                  REFRESH_INTERVAL_IN_SECOND), ex);
+          logger.warn("Refreshing meta server address failed, will retry in {} seconds", REFRESH_INTERVAL_IN_SECOND, ex);
         }
       }
     }, REFRESH_INTERVAL_IN_SECOND, REFRESH_INTERVAL_IN_SECOND, TimeUnit.SECONDS);

apollo-core/src/main/java/com/ctrip/framework/apollo/core/signature/Signature.java

@@ -60,7 +60,7 @@ private static String url2PathWithQuery(String urlString) {
       String query = url.getQuery();
 
       String pathWithQuery = path;
-      if (query != null && query.length() > 0) {
+      if (query != null && !query.isEmpty()) {
         pathWithQuery += "?" + query;
       }
       return pathWithQuery;

apollo-core/src/main/java/com/ctrip/framework/apollo/core/utils/ApolloThreadFactory.java

@@ -60,7 +60,7 @@ public boolean satisfy(Thread thread) {
           return !thread.isAlive() || thread.isInterrupted() || thread.isDaemon();
         }
       });
-      if (alives.size() > 0) {
+      if (!alives.isEmpty()) {
         log.info("Alive apollo threads: {}", alives);
         try {
           TimeUnit.SECONDS.sleep(2);

apollo-core/src/main/java/com/ctrip/framework/apollo/core/utils/ResourceUtils.java

@@ -65,7 +65,7 @@ public static Properties readConfigFile(String configPath, Properties defaults)
 
       }
       if (sb.length() > 0) {
-        logger.debug("Reading properties: \n" + sb);
+        logger.debug("Reading properties: \n{}", sb);
       } else {
         logger.warn("No available properties: {}", configPath);
       }

apollo-core/src/main/java/com/ctrip/framework/apollo/core/utils/StringUtils.java

@@ -41,7 +41,7 @@ public class StringUtils {
    * @return <code>true</code> if the String is empty or null
    */
   public static boolean isEmpty(String str) {
-    return str == null || str.length() == 0;
+    return str == null || str.isEmpty();
   }
 
 

apollo-openapi/src/main/java/com/ctrip/framework/apollo/openapi/dto/OpenPageDTO.java

@@ -53,7 +53,7 @@ public List<T> getContent() {
     }
 
     public boolean hasContent() {
-        return content != null && content.size() > 0;
+        return content != null && !content.isEmpty();
     }
 
 }