fix: format and clean code in dist and example modules

[msgui]

Purpose of the PR

• subtask of [Summary] Enhance code style warnings in server #2435

Main Changes

Format & clean code in submodels:

1. Dist
2. Example

Verifying these changes

• Trivial rework / code cleanup without any test coverage. (No Need)
• Already covered by existing tests, such as (please modify tests here).
• Need tests and can be verified as follows:
  • xxx

Does this PR potentially affect the following parts?

• Nope
• Dependencies (add/update license info)
• Modify configurations
• The public API
• Other affects (typed here)

Documentation Status

• Doc - TODO
• Doc - Done
• Doc - No Need

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (7586779) 66.21% compared to head (e70afb7) 66.26%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2441      +/-   ##
============================================
+ Coverage     66.21%   66.26%   +0.04%     
- Complexity      828      830       +2     
============================================
  Files           511      511              
  Lines         42598    42598              
  Branches       5942     5942              
============================================
+ Hits          28208    28229      +21     
+ Misses        11582    11555      -27     
- Partials       2808     2814       +6     

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[VGalaxies]

@msgui What are the steps for code formatting? Here's what I do:

1. First, import the hugegraph-style.xml modified through chore: refine the hg-style.xml specification #2436 and apply it.

2. Right-click on the hugegraph-dist directory and select "reformat code".

3. Check the following options and reformat.

But I ended up with different modifications. Which step went wrong?

diff --git a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/ConfDumper.java b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/ConfDumper.java
index cdeb3214..ded5a913 100644
--- a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/ConfDumper.java
+++ b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/ConfDumper.java
@@ -23,14 +23,13 @@ import java.util.TreeSet;
 
 import org.apache.commons.configuration.ConfigurationException;
 import org.apache.commons.io.FileUtils;
-import org.apache.hugegraph.dist.RegisterUtil;
-import org.slf4j.Logger;
-
 import org.apache.hugegraph.config.HugeConfig;
 import org.apache.hugegraph.config.OptionSpace;
 import org.apache.hugegraph.config.TypedOption;
+import org.apache.hugegraph.dist.RegisterUtil;
 import org.apache.hugegraph.util.E;
 import org.apache.hugegraph.util.Log;
+import org.slf4j.Logger;
 
 public class ConfDumper {
 
@@ -39,7 +38,7 @@ public class ConfDumper {
     private static final Logger LOG = Log.logger(ConfDumper.class);
 
     public static void main(String[] args)
-                       throws ConfigurationException, IOException {
+        throws ConfigurationException, IOException {
         E.checkArgument(args.length == 1,
                         "ConfDumper need a config file.");
 
diff --git a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/InitStore.java b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/InitStore.java
index 75199d1e..3e84f735 100644
--- a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/InitStore.java
+++ b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/InitStore.java
@@ -117,9 +117,10 @@ public class InitStore {
     }
 
     private static void initBackend(final HugeGraph graph)
-                                    throws InterruptedException {
+        throws InterruptedException {
         int retries = RETRIES;
-        retry: do {
+        retry:
+        do {
             try {
                 graph.initBackend();
             } catch (Exception e) {
diff --git a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/StoreDumper.java b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/StoreDumper.java
index 352ea0b0..a78c2d6e 100644
--- a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/StoreDumper.java
+++ b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/cmd/StoreDumper.java
@@ -34,14 +34,39 @@ import org.slf4j.Logger;
 
 public class StoreDumper {
 
-    private final HugeGraph graph;
-
     private static final Logger LOG = Log.logger(StoreDumper.class);
+    private final HugeGraph graph;
 
     public StoreDumper(String conf) {
         this.graph = HugeFactory.open(conf);
     }
 
+    public static void main(String[] args) throws Exception {
+        E.checkArgument(args.length >= 1,
+                        "StoreDumper need a config file.");
+
+        String conf = args[0];
+        RegisterUtil.registerBackends();
+
+        HugeType table = HugeType.valueOf(arg(args, 1, "VERTEX").toUpperCase());
+        long offset = Long.parseLong(arg(args, 2, "0"));
+        long limit = Long.parseLong(arg(args, 3, "20"));
+
+        StoreDumper dumper = new StoreDumper(conf);
+        dumper.dump(table, offset, limit);
+        dumper.close();
+
+        // Stop daemon thread
+        HugeFactory.shutdown(30L, true);
+    }
+
+    private static String arg(String[] args, int index, String deflt) {
+        if (index < args.length) {
+            return args[index];
+        }
+        return deflt;
+    }
+
     public void dump(HugeType table, long offset, long limit) {
         BackendStore store = this.backendStore(table);
 
@@ -70,30 +95,4 @@ public class StoreDumper {
     public void close() throws Exception {
         this.graph.close();
     }
-
-    public static void main(String[] args) throws Exception {
-        E.checkArgument(args.length >= 1,
-                        "StoreDumper need a config file.");
-
-        String conf = args[0];
-        RegisterUtil.registerBackends();
-
-        HugeType table = HugeType.valueOf(arg(args, 1, "VERTEX").toUpperCase());
-        long offset = Long.parseLong(arg(args, 2, "0"));
-        long limit = Long.parseLong(arg(args, 3, "20"));
-
-        StoreDumper dumper = new StoreDumper(conf);
-        dumper.dump(table, offset, limit);
-        dumper.close();
-
-        // Stop daemon thread
-        HugeFactory.shutdown(30L, true);
-    }
-
-    private static String arg(String[] args, int index, String deflt) {
-        if (index < args.length) {
-            return args[index];
-        }
-        return deflt;
-    }
 }
diff --git a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/DistOptions.java b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/DistOptions.java
index 6766d5f9..03ce96f7 100644
--- a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/DistOptions.java
+++ b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/DistOptions.java
@@ -24,12 +24,19 @@ import org.apache.hugegraph.config.OptionHolder;
 
 public class DistOptions extends OptionHolder {
 
+    public static final ConfigListOption<String> BACKENDS =
+        new ConfigListOption<>(
+            "backends",
+            "The all data store type.",
+            disallowEmpty(),
+            "memory"
+        );
+    private static volatile DistOptions instance;
+
     private DistOptions() {
         super();
     }
 
-    private static volatile DistOptions instance;
-
     public static synchronized DistOptions instance() {
         if (instance == null) {
             instance = new DistOptions();
@@ -37,12 +44,4 @@ public class DistOptions extends OptionHolder {
         }
         return instance;
     }
-
-    public static final ConfigListOption<String> BACKENDS =
-            new ConfigListOption<>(
-                    "backends",
-                    "The all data store type.",
-                    disallowEmpty(),
-                    "memory"
-            );
 }
diff --git a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeGraphServer.java b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeGraphServer.java
index 7af1ff8b..4f34447c 100644
--- a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeGraphServer.java
+++ b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeGraphServer.java
@@ -38,14 +38,8 @@ public class HugeGraphServer {
     private final RestServer restServer;
     private final GremlinServer gremlinServer;
 
-    public static void register() {
-        RegisterUtil.registerBackends();
-        RegisterUtil.registerPlugins();
-        RegisterUtil.registerServer();
-    }
-
     public HugeGraphServer(String gremlinServerConf, String restServerConf)
-                           throws Exception {
+        throws Exception {
         // Only switch on security manager after HugeGremlinServer started
         SecurityManager securityManager = System.getSecurityManager();
         System.setSecurityManager(null);
@@ -80,27 +74,10 @@ public class HugeGraphServer {
         }
     }
 
-    public void stop() {
-        try {
-            this.gremlinServer.stop().get();
-            LOG.info("HugeGremlinServer stopped");
-        } catch (Throwable e) {
-            LOG.error("HugeGremlinServer stop error: ", e);
-        }
-
-        try {
-            this.restServer.shutdown().get();
-            LOG.info("HugeRestServer stopped");
-        } catch (Throwable e) {
-            LOG.error("HugeRestServer stop error: ", e);
-        }
-
-        try {
-            HugeFactory.shutdown(30L);
-            LOG.info("HugeGraph stopped");
-        } catch (Throwable e) {
-            LOG.error("Failed to stop HugeGraph: ", e);
-        }
+    public static void register() {
+        RegisterUtil.registerBackends();
+        RegisterUtil.registerPlugins();
+        RegisterUtil.registerServer();
     }
 
     public static void main(String[] args) throws Exception {
@@ -143,4 +120,27 @@ public class HugeGraphServer {
         // Wait for server-shutdown and server-stopped
         serverStopped.get();
     }
+
+    public void stop() {
+        try {
+            this.gremlinServer.stop().get();
+            LOG.info("HugeGremlinServer stopped");
+        } catch (Throwable e) {
+            LOG.error("HugeGremlinServer stop error: ", e);
+        }
+
+        try {
+            this.restServer.shutdown().get();
+            LOG.info("HugeRestServer stopped");
+        } catch (Throwable e) {
+            LOG.error("HugeRestServer stop error: ", e);
+        }
+
+        try {
+            HugeFactory.shutdown(30L);
+            LOG.info("HugeGraph stopped");
+        } catch (Throwable e) {
+            LOG.error("Failed to stop HugeGraph: ", e);
+        }
+    }
 }
diff --git a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeGremlinServer.java b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeGremlinServer.java
index 7d7a992a..edc4391e 100644
--- a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeGremlinServer.java
+++ b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeGremlinServer.java
@@ -17,16 +17,15 @@
 
 package org.apache.hugegraph.dist;
 
-import org.apache.tinkerpop.gremlin.server.GremlinServer;
-import org.apache.tinkerpop.gremlin.server.Settings;
-import org.slf4j.Logger;
-
 import org.apache.hugegraph.HugeException;
 import org.apache.hugegraph.auth.ContextGremlinServer;
 import org.apache.hugegraph.event.EventHub;
 import org.apache.hugegraph.util.ConfigUtil;
 import org.apache.hugegraph.util.E;
 import org.apache.hugegraph.util.Log;
+import org.apache.tinkerpop.gremlin.server.GremlinServer;
+import org.apache.tinkerpop.gremlin.server.Settings;
+import org.slf4j.Logger;
 
 public class HugeGremlinServer {
 
diff --git a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeRestServer.java b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeRestServer.java
index 395ae886..6edb818b 100644
--- a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeRestServer.java
+++ b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/HugeRestServer.java
@@ -17,11 +17,10 @@
 
 package org.apache.hugegraph.dist;
 
-import org.slf4j.Logger;
-
 import org.apache.hugegraph.event.EventHub;
 import org.apache.hugegraph.server.RestServer;
 import org.apache.hugegraph.util.Log;
+import org.slf4j.Logger;
 
 public class HugeRestServer {
 
diff --git a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/RegisterUtil.java b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/RegisterUtil.java
index a760c7c0..06b8fe28 100644
--- a/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/RegisterUtil.java
+++ b/hugegraph-server/hugegraph-dist/src/main/java/org/apache/hugegraph/dist/RegisterUtil.java
@@ -102,10 +102,12 @@ public class RegisterUtil {
                              "org.apache.hugegraph.backend.store.cassandra.CassandraOptions");
         // Register serializer
         SerializerFactory.register("cassandra",
-                "org.apache.hugegraph.backend.store.cassandra.CassandraSerializer");
+                                   "org.apache.hugegraph.backend.store.cassandra" +
+                                   ".CassandraSerializer");
         // Register backend
         BackendProviderFactory.register("cassandra",
-                "org.apache.hugegraph.backend.store.cassandra.CassandraStoreProvider");
+                                        "org.apache.hugegraph.backend.store.cassandra" +
+                                        ".CassandraStoreProvider");
     }
 
     public static void registerScyllaDB() {
@@ -114,10 +116,12 @@ public class RegisterUtil {
                              "org.apache.hugegraph.backend.store.cassandra.CassandraOptions");
         // Register serializer
         SerializerFactory.register("scylladb",
-                "org.apache.hugegraph.backend.store.cassandra.CassandraSerializer");
+                                   "org.apache.hugegraph.backend.store.cassandra" +
+                                   ".CassandraSerializer");
         // Register backend
         BackendProviderFactory.register("scylladb",
-                "org.apache.hugegraph.backend.store.scylladb.ScyllaDBStoreProvider");
+                                        "org.apache.hugegraph.backend.store.scylladb" +
+                                        ".ScyllaDBStoreProvider");
     }
 
     public static void registerHBase() {
@@ -129,7 +133,8 @@ public class RegisterUtil {
                                    "org.apache.hugegraph.backend.store.hbase.HbaseSerializer");
         // Register backend
         BackendProviderFactory.register("hbase",
-                "org.apache.hugegraph.backend.store.hbase.HbaseStoreProvider");
+                                        "org.apache.hugegraph.backend.store.hbase" +
+                                        ".HbaseStoreProvider");
     }
 
     public static void registerRocksDB() {
@@ -138,9 +143,11 @@ public class RegisterUtil {
                              "org.apache.hugegraph.backend.store.rocksdb.RocksDBOptions");
         // Register backend
         BackendProviderFactory.register("rocksdb",
-                "org.apache.hugegraph.backend.store.rocksdb.RocksDBStoreProvider");
+                                        "org.apache.hugegraph.backend.store.rocksdb" +
+                                        ".RocksDBStoreProvider");
         BackendProviderFactory.register("rocksdbsst",
-                "org.apache.hugegraph.backend.store.rocksdbsst.RocksDBSstStoreProvider");
+                                        "org.apache.hugegraph.backend.store.rocksdbsst" +
+                                        ".RocksDBSstStoreProvider");
     }
 
     public static void registerMysql() {
@@ -152,7 +159,8 @@ public class RegisterUtil {
                                    "org.apache.hugegraph.backend.store.mysql.MysqlSerializer");
         // Register backend
         BackendProviderFactory.register("mysql",
-                "org.apache.hugegraph.backend.store.mysql.MysqlStoreProvider");
+                                        "org.apache.hugegraph.backend.store.mysql" +
+                                        ".MysqlStoreProvider");
     }
 
     public static void registerPalo() {
@@ -161,22 +169,25 @@ public class RegisterUtil {
                              "org.apache.hugegraph.backend.store.palo.PaloOptions");
         // Register serializer
         SerializerFactory.register("palo",
-                "org.apache.hugegraph.backend.store.palo.PaloSerializer");
+                                   "org.apache.hugegraph.backend.store.palo.PaloSerializer");
         // Register backend
         BackendProviderFactory.register("palo",
-                "org.apache.hugegraph.backend.store.palo.PaloStoreProvider");
+                                        "org.apache.hugegraph.backend.store.palo" +
+                                        ".PaloStoreProvider");
     }
 
     public static void registerPostgresql() {
         // Register config
         OptionSpace.register("postgresql",
-                "org.apache.hugegraph.backend.store.postgresql.PostgresqlOptions");
+                             "org.apache.hugegraph.backend.store.postgresql.PostgresqlOptions");
         // Register serializer
         SerializerFactory.register("postgresql",
-                "org.apache.hugegraph.backend.store.postgresql.PostgresqlSerializer");
+                                   "org.apache.hugegraph.backend.store.postgresql" +
+                                   ".PostgresqlSerializer");
         // Register backend
         BackendProviderFactory.register("postgresql",
-                "org.apache.hugegraph.backend.store.postgresql.PostgresqlStoreProvider");
+                                        "org.apache.hugegraph.backend.store.postgresql" +
+                                        ".PostgresqlStoreProvider");
     }
 
     public static void registerServer() {

[msgui]

@VGalaxies
please wait, wip~