Code cleanup.

23 files changed, 98 insertions, 312 deletions

diff --git a/src/main/java/com/keuin/kbackupfabric/KBCommandsRegister.java b/src/main/java/com/keuin/kbackupfabric/KBCommandsRegister.java
index b502ad5..154a39f 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBCommandsRegister.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBCommandsRegister.java
@@ -85,7 +85,5 @@ public final class KBCommandsRegister {
                         .requires(Permissions.require("kb.prev", DEFAULT_REQUIRED_LEVEL))
                         .executes(KBCommands::prev)));
 
-//        // register /kb setMethod for selecting backup method (zip, incremental)
-//        dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("setMethod").then(CommandManager.argument("backupMethod", StringArgumentType.string()).suggests(BackupMethodSuggestionProvider.getProvider()).requires(PermissionValidator::op).executes(KBCommands::setMethod))));
     }
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/KBConfiguration.java b/src/main/java/com/keuin/kbackupfabric/KBConfiguration.java
index 3744430..54b4348 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBConfiguration.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBConfiguration.java
@@ -6,7 +6,7 @@ package com.keuin.kbackupfabric;
 public class KBConfiguration {
     // auto backup interval in seconds. Set this to a negative value to disable auto backup.
     private final int autoBackupIntervalSeconds;
-    // name of backup created automatically. By default it is `auto-backup`
+    // name of backup created automatically. By default, it is `auto-backup`
     private final String autoBackupName;
     // if no player has logged in since previous backup, we skip this backup
     private final boolean skipAutoBackupIfNoPlayerLoggedIn;
diff --git a/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java b/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
index 2b2865e..d09b9e9 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
@@ -60,7 +60,7 @@ public final class KBPluginEvents implements ModInitializer, ServerStartCallback
 
         // Check if we have just recovered from a previous backup. If so, print message.
         try {
-            File levelDirectory = new File(server.getRunDirectory(), ((MinecraftDedicatedServer) server).getLevelName());
+            File levelDirectory = new File(server.getRunDirectory(), server.getLevelName());
             File metadataFile = new File(levelDirectory, BackupMetadata.metadataFileName);
             if (metadataFile.exists()) {
                 // Metadata exists. Deserialize.
diff --git a/src/main/java/com/keuin/kbackupfabric/backup/BackupFilesystemUtil.java b/src/main/java/com/keuin/kbackupfabric/backup/BackupFilesystemUtil.java
index eac7ce9..519951a 100644
--- a/src/main/java/com/keuin/kbackupfabric/backup/BackupFilesystemUtil.java
+++ b/src/main/java/com/keuin/kbackupfabric/backup/BackupFilesystemUtil.java
@@ -26,17 +26,6 @@ public final class BackupFilesystemUtil {
         return backupFileNamePrefix;
     }
 
-
-//    @Deprecated
-//    public static String getBackupName(String backupFileName) {
-//        try {
-//            if (backupFileName.matches(backupFileNamePrefix + ".+\\.zip"))
-//                return backupFileName.substring(backupFileNamePrefix.length(), backupFileName.length() - 4);
-//        } catch (IndexOutOfBoundsException ignored) {
-//        }
-//        return backupFileName;
-//    }
-
     public static boolean isBackupFileExists(String backupFileName, MinecraftServer server) {
         File backupFile = new File(getBackupSaveDirectory(server), backupFileName);
         return backupFile.isFile();
diff --git a/src/main/java/com/keuin/kbackupfabric/backup/incremental/ObjectCollectionFactory.java b/src/main/java/com/keuin/kbackupfabric/backup/incremental/ObjectCollectionFactory.java
index 04ae96e..095108b 100644
--- a/src/main/java/com/keuin/kbackupfabric/backup/incremental/ObjectCollectionFactory.java
+++ b/src/main/java/com/keuin/kbackupfabric/backup/incremental/ObjectCollectionFactory.java
@@ -13,6 +13,7 @@ import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
+import java.util.stream.Stream;
 
 /**
  * Incremental backup is implemented as git-like file collection.
@@ -45,17 +46,19 @@ public class ObjectCollectionFactory<T extends ObjectIdentifier> {
             throw new IllegalArgumentException("given file is not a directory");
 
         Set<File> files = new HashSet<>();
-        for (Iterator<Path> iter = Files.walk(directory.toPath(), 1).iterator(); iter.hasNext(); ) {
-            Path path = iter.next();
-            if (Files.isSameFile(path, directory.toPath()))
-                continue;
-            File file = path.toFile();
-            if (file.isDirectory()) {
-                subCollections.put(file.getName(), fromDirectory(file, ignoredFiles));
-            } else if (!ignoredFiles.contains(file.getName())) {
-                files.add(file); // add to the set to be processed
-            } else {
-                PrintUtil.info(String.format("Skipping file %s.", file.getName()));
+        try (Stream<Path> walk = Files.walk(directory.toPath(), 1)) {
+            for (Iterator<Path> iter = walk.iterator(); iter.hasNext(); ) {
+                Path path = iter.next();
+                if (Files.isSameFile(path, directory.toPath()))
+                    continue;
+                File file = path.toFile();
+                if (file.isDirectory()) {
+                    subCollections.put(file.getName(), fromDirectory(file, ignoredFiles));
+                } else if (!ignoredFiles.contains(file.getName())) {
+                    files.add(file); // add to the set to be processed
+                } else {
+                    PrintUtil.info(String.format("Skipping file %s.", file.getName()));
+                }
             }
         }
 
@@ -125,7 +128,7 @@ public class ObjectCollectionFactory<T extends ObjectIdentifier> {
         public void process() {
             workers.clear();
             for (int i = 0; i < threads; i++) {
-                ParallelWorker<Res> worker = new ParallelWorker<Res>(taskList, consumer, i);
+                ParallelWorker<Res> worker = new ParallelWorker<>(taskList, consumer, i);
                 workers.add(worker);
                 worker.start();
             }
diff --git a/src/main/java/com/keuin/kbackupfabric/backup/incremental/ObjectCollectionSerializer.java b/src/main/java/com/keuin/kbackupfabric/backup/incremental/ObjectCollectionSerializer.java
index 42e7c0c..7a395d8 100644
--- a/src/main/java/com/keuin/kbackupfabric/backup/incremental/ObjectCollectionSerializer.java
+++ b/src/main/java/com/keuin/kbackupfabric/backup/incremental/ObjectCollectionSerializer.java
@@ -21,17 +21,6 @@ public class ObjectCollectionSerializer {
     @Deprecated
     public static ObjectCollection2 fromFile(File file) throws IOException {
         throw new RuntimeException("This method has been depreciated.");
-//        Objects.requireNonNull(file);
-//        ObjectCollection2 collection;
-//        try (FileInputStream fileInputStream = new FileInputStream(file)) {
-//            try (ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream)) {
-//                collection = (ObjectCollection2) objectInputStream.readObject();
-//            } catch (ClassNotFoundException ignored) {
-//                // this should not happen
-//                return null;
-//            }
-//        }
-//        return collection;
     }
 
     /**
diff --git a/src/main/java/com/keuin/kbackupfabric/backup/incremental/identifier/Sha256Identifier.java b/src/main/java/com/keuin/kbackupfabric/backup/incremental/identifier/Sha256Identifier.java
index 50e6aa4..21111a0 100644
--- a/src/main/java/com/keuin/kbackupfabric/backup/incremental/identifier/Sha256Identifier.java
+++ b/src/main/java/com/keuin/kbackupfabric/backup/incremental/identifier/Sha256Identifier.java
@@ -54,27 +54,20 @@ public class Sha256Identifier extends SingleHashIdentifier {
 
     @Override
     protected byte[] hash(File file) throws IOException {
+        return sha256Hash(file);
+    }
+
+    public static byte[] sha256Hash(File file) throws IOException {
         try {
             MessageDigest digest = MessageDigest.getInstance("SHA-256");
 
             try (FileInputStream inputStream = new FileInputStream(file)) {
-                // This does not work. I don't know why
-//            FileChannel channel = inputStream.getChannel();
-//            ByteBuffer buffer = ByteBuffer.allocate(128);
-//            int readLength;
-//            while ((readLength = channel.read(buffer)) > 0)
-//                digest.update(buffer);
-
-                // This also works, without warnings
                 byte[] readBuffer = new byte[1024 * 1024];
+
                 int readLength;
-                while ((readLength = inputStream.read(readBuffer)) > 0)
+                while ((readLength = inputStream.read(readBuffer)) > 0) {
                     digest.update(readBuffer, 0, readLength);
-
-                // The below lines also works, but the IDE will complain about the while loop
-//            DigestInputStream digestInputStream = new DigestInputStream(inputStream, digest);
-//            while(digestInputStream.read() > 0)
-//                ;
+                }
 
                 return digest.digest();
             }
diff --git a/src/main/java/com/keuin/kbackupfabric/backup/incremental/manager/IncrementalBackupStorageManager.java b/src/main/java/com/keuin/kbackupfabric/backup/incremental/manager/IncrementalBackupStorageManager.java
index b18c119..7870620 100644
--- a/src/main/java/com/keuin/kbackupfabric/backup/incremental/manager/IncrementalBackupStorageManager.java
+++ b/src/main/java/com/keuin/kbackupfabric/backup/incremental/manager/IncrementalBackupStorageManager.java
@@ -47,7 +47,7 @@ public class IncrementalBackupStorageManager {
      * Check whether the storage contains all files in the given collection.
      *
      * @param collection the collection.
-     * @return whether all files exists.
+     * @return whether all files exist.
      */
     public boolean contains(@NotNull ObjectCollection2 collection) {
         Objects.requireNonNull(collection);
@@ -60,7 +60,7 @@ public class IncrementalBackupStorageManager {
     }
 
     /**
-     * Add a object collection to storage base and copy files to the storage.
+     * Add an object collection to storage base and copy files to the storage.
      *
      * @param collection the collection.
      * @return objects copied to the base.
diff --git a/src/main/java/com/keuin/kbackupfabric/backup/incremental/serializer/IncBackupInfoSerializer.java b/src/main/java/com/keuin/kbackupfabric/backup/incremental/serializer/IncBackupInfoSerializer.java
index f17217a..c5d1115 100644
--- a/src/main/java/com/keuin/kbackupfabric/backup/incremental/serializer/IncBackupInfoSerializer.java
+++ b/src/main/java/com/keuin/kbackupfabric/backup/incremental/serializer/IncBackupInfoSerializer.java
@@ -13,6 +13,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
+import java.util.stream.Stream;
 
 public class IncBackupInfoSerializer {
     /**
@@ -77,10 +78,12 @@ public class IncBackupInfoSerializer {
             throw new IllegalArgumentException("Given directory is invalid.");
         }
         List<Path> pathList = new ArrayList<>();
-        Files.walk(directory.toPath(), 1).filter(p -> {
-            File f = p.toFile();
-            return f.isFile() && f.getName().endsWith(".kbi");
-        }).forEach(pathList::add);
+        try (Stream<Path> walk = Files.walk(directory.toPath(), 1)) {
+            walk.filter(p -> {
+                File f = p.toFile();
+                return f.isFile() && f.getName().endsWith(".kbi");
+            }).forEach(pathList::add);
+        }
         List<SavedIncrementalBackup> objectList = new ArrayList<>();
         for (Path path : pathList) {
             SavedIncrementalBackup info = IncBackupInfoSerializer.fromFile(path.toFile());
diff --git a/src/main/java/com/keuin/kbackupfabric/backup/suggestion/BackupNameSuggestionProvider.java b/src/main/java/com/keuin/kbackupfabric/backup/suggestion/BackupNameSuggestionProvider.java
index 9c0c1c2..fa38979 100644
--- a/src/main/java/com/keuin/kbackupfabric/backup/suggestion/BackupNameSuggestionProvider.java
+++ b/src/main/java/com/keuin/kbackupfabric/backup/suggestion/BackupNameSuggestionProvider.java
@@ -47,11 +47,6 @@ public class BackupNameSuggestionProvider {
         }
     }
 
-//    private static void updateCandidateList(Collection<String> stringCollection) {
-//        candidateList.clear();
-//        candidateList.addAll(stringCollection);
-//    }
-
     public static SuggestionProvider<ServerCommandSource> getProvider() {
 //        return (context, builder) -> getCompletableFuture(builder);
         return (context, builder) -> {
@@ -61,24 +56,6 @@ public class BackupNameSuggestionProvider {
         };
     }
 
-//    private static CompletableFuture<Suggestions> getCompletableFuture(SuggestionsBuilder builder) {
-//        if (isCacheExpired())
-//            updateCandidateList();
-//        String remaining = builder.getRemaining().toLowerCase(Locale.ROOT);
-//        synchronized (syncCache) {
-//            if (candidateCacheList.isEmpty()) { // If the list is empty then return no suggestions
-//                return Suggestions.empty(); // No suggestions
-//            }
-//
-//            for (String string : candidateCacheList) { // Iterate through the supplied list
-//                if (string.toLowerCase(Locale.ROOT).startsWith(remaining)) {
-//                    builder.suggest(string); // Add every single entry to suggestions list.
-//                }
-//            }
-//        }
-//        return builder.buildFuture(); // Create the CompletableFuture containing all the suggestions
-//    }
-
     private static boolean isCacheExpired() {
         return ((int) System.currentTimeMillis()) - cacheUpdateTime > CACHE_TTL || cacheUpdateTime == 0;
     }
diff --git a/src/main/java/com/keuin/kbackupfabric/notification/DistinctNotifiable.java b/src/main/java/com/keuin/kbackupfabric/notification/DistinctNotifiable.java
index b44bfce..6d45e26 100644
--- a/src/main/java/com/keuin/kbackupfabric/notification/DistinctNotifiable.java
+++ b/src/main/java/com/keuin/kbackupfabric/notification/DistinctNotifiable.java
@@ -17,7 +17,7 @@ public interface DistinctNotifiable {
     void notify(Text text);
 
     /**
-     * Get an unique, non-null object that identifies this notifiable instance.
+     * Get a unique, non-null object that identifies this notifiable instance.
      * The identifier must be immutable and implement their own equals method.
      *
      * @return the identifier.
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/BackupOperation.java b/src/main/java/com/keuin/kbackupfabric/operation/BackupOperation.java
index 1798fb7..3fec8b9 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/BackupOperation.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/BackupOperation.java
@@ -33,7 +33,7 @@ public class BackupOperation extends InvokableAsyncBlockingOperation {
     protected void async() {
         String backupSaveDirectory = "";
         MinecraftServer server = context.getSource().getMinecraftServer();
-        boolean success = false; // only success when everything is done
+        boolean success; // only success when everything is done
         try {
             //// Do our main backup logic
 
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/abstracts/AbstractAsyncOperation.java b/src/main/java/com/keuin/kbackupfabric/operation/abstracts/AbstractAsyncOperation.java
index bb0c704..2dac710 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/abstracts/AbstractAsyncOperation.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/abstracts/AbstractAsyncOperation.java
@@ -2,7 +2,7 @@ package com.keuin.kbackupfabric.operation.abstracts;
 
 /**
  * A basic async operation, but not invokable.
- * If you want a invokable interface (InvokableOperation), use InvokableAsyncOperation instead.
+ * If you want an invokable interface (InvokableOperation), use InvokableAsyncOperation instead.
  */
 public abstract class AbstractAsyncOperation extends AbstractSerialOperation {
 
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/abstracts/AbstractSerialOperation.java b/src/main/java/com/keuin/kbackupfabric/operation/abstracts/AbstractSerialOperation.java
index 92dfb53..db5433f 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/abstracts/AbstractSerialOperation.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/abstracts/AbstractSerialOperation.java
@@ -2,7 +2,7 @@ package com.keuin.kbackupfabric.operation.abstracts;
 
 /**
  * The most basic operation abstraction.
- * This class represents an serial operation, which is limited in a non-public method.
+ * This class represents a serial operation, which is limited in a non-public method.
  * Note that the operation is not invokable by default, you should use InvokableOperation in order to provide a public method for users to call.
  */
 public abstract class AbstractSerialOperation {
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/backup/method/ConfiguredIncrementalBackupMethod.java b/src/main/java/com/keuin/kbackupfabric/operation/backup/method/ConfiguredIncrementalBackupMethod.java
index 2cc0765..cfc9b81 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/backup/method/ConfiguredIncrementalBackupMethod.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/backup/method/ConfiguredIncrementalBackupMethod.java
@@ -99,7 +99,6 @@ public class ConfiguredIncrementalBackupMethod implements ConfiguredBackupMethod
             PrintUtil.info("Incremental backup finished.");
             feedback = new IncrementalBackupFeedback(true, copyResult);
         } catch (IOException e) {
-//            e.printStackTrace(); // stack trace has been passed to backup feedback. No need to print here.
             feedback = new IncrementalBackupFeedback(e);
         }
 
@@ -119,7 +118,7 @@ public class ConfiguredIncrementalBackupMethod implements ConfiguredBackupMethod
             // remove unused object files in the base
             if (collection != null) {
                 try {
-                    // collection may have been copied (partially) to the base, but we may not need them
+                    // collection may have been copied (partially) to the base, but we may not need them,
                     // so we perform a clean here
                     // perform a clean-up
                     Iterable<ObjectCollection2> backups = ObjectCollectionSerializer.fromDirectory(new File(backupIndexFileSaveDirectory));
diff --git a/src/main/java/com/keuin/kbackupfabric/ui/BackupManager.java b/src/main/java/com/keuin/kbackupfabric/ui/BackupManager.java
index d4081c6..7ee46f9 100644
--- a/src/main/java/com/keuin/kbackupfabric/ui/BackupManager.java
+++ b/src/main/java/com/keuin/kbackupfabric/ui/BackupManager.java
@@ -1,7 +1,5 @@
 package com.keuin.kbackupfabric.ui;
 
-import org.jetbrains.annotations.NotNull;
-
 import java.io.File;
 import java.io.IOException;
 import java.util.Arrays;
@@ -28,51 +26,47 @@ public class BackupManager {
      * @return all backups.
      */
     public Iterable<BackupInfo> getAllBackups() {
-        return new Iterable<BackupInfo>() {
-            @NotNull
-            @Override
-            public Iterator<BackupInfo> iterator() {
-                if (backupStorageDirectory.exists()) {
-                    if (!backupStorageDirectory.isDirectory()) {
-                        throw new RuntimeException("Backup directory is not a directory.");
-                    }
-                } else {
-                    if (!backupStorageDirectory.mkdirs()) {
-                        throw new RuntimeException("Backup directory does not exist and cannot be created.");
-                    }
+        return () -> {
+            if (backupStorageDirectory.exists()) {
+                if (!backupStorageDirectory.isDirectory()) {
+                    throw new RuntimeException("Backup directory is not a directory.");
                 }
-                File[] backupFiles = backupStorageDirectory.listFiles();
-                if (backupFiles == null) {
-                    throw new RuntimeException("Cannot list files in backup directory.");
+            } else {
+                if (!backupStorageDirectory.mkdirs()) {
+                    throw new RuntimeException("Backup directory does not exist and cannot be created.");
                 }
+            }
+            File[] backupFiles = backupStorageDirectory.listFiles();
+            if (backupFiles == null) {
+                throw new RuntimeException("Cannot list files in backup directory.");
+            }
 
-                return new Iterator<BackupInfo>() {
-                    private final Iterator<File> fileIterator = Arrays.stream(backupFiles).filter(file -> {
-                        String name = file.getName().toLowerCase();
-                        return name.endsWith(".zip") || name.endsWith(".kbi");
-                    }).iterator();
+            return new Iterator<BackupInfo>() {
+                private final Iterator<File> fileIterator = Arrays.stream(backupFiles).filter(file -> {
+                    String name = file.getName().toLowerCase();
+                    return name.endsWith(".zip") || name.endsWith(".kbi");
+                }).iterator();
 
-                    @Override
-                    public boolean hasNext() {
-                        return fileIterator.hasNext();
-                    }
+                @Override
+                public boolean hasNext() {
+                    return fileIterator.hasNext();
+                }
 
-                    @Override
-                    public BackupInfo next() {
-                        try {
-                            File backupFile = fileIterator.next();
-                            String fileName = backupFile.getName().toLowerCase();
-                            if (fileName.endsWith(".zip"))
-                                return PrimitiveBackupInfo.fromFile(backupFile);
-                            if (fileName.endsWith(".kbi"))
-                                return IncrementalBackupInfo.fromFile(backupFile);
-                            throw new RuntimeException("Invalid backup file extname");
-                        } catch (IOException e) {
-                            throw new RuntimeException(e);
-                        }
+                @Override
+                public BackupInfo next() {
+                    try {
+                        File backupFile = fileIterator.next();
+                        String fileName = backupFile.getName().toLowerCase();
+                        if (fileName.endsWith(".zip"))
+                            return PrimitiveBackupInfo.fromFile(backupFile);
+                        if (fileName.endsWith(".kbi"))
+                            return IncrementalBackupInfo.fromFile(backupFile);
+                        throw new RuntimeException("Invalid backup file extname");
+                    } catch (IOException e) {
+                        throw new RuntimeException(e);
                     }
-                };
-            }
+                }
+            };
         };
     }
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/ui/KBCommands.java b/src/main/java/com/keuin/kbackupfabric/ui/KBCommands.java
index e148f24..d23a6fd 100644
--- a/src/main/java/com/keuin/kbackupfabric/ui/KBCommands.java
+++ b/src/main/java/com/keuin/kbackupfabric/ui/KBCommands.java
@@ -40,12 +40,8 @@ public final class KBCommands {
     private static MinecraftServer server;
     private static BackupManager backupManager;
     private static final Object managerCreatorLock = new Object();
-
-    //private static final Logger LOGGER = LogManager.getLogger();
-
     private static final List<BackupInfo> backupList = new ArrayList<>(); // index -> backupName
     private static Invokable pendingOperation = null;
-    //private static BackupMethod activatedBackupMethod = new PrimitiveBackupMethod(); // The backup method we currently using
 
     public static void setServer(MinecraftServer server) {
         KBCommands.server = server;
@@ -124,21 +120,6 @@ public final class KBCommands {
         // TODO: Show concrete info from metadata for `.zip` backup
 //        MinecraftServer server = context.getSource().getMinecraftServer();
         // TODO: refactor this to use {@link ObjectCollectionSerializer#fromDirectory}
-//        File[] files = getBackupSaveDirectory(server).listFiles(
-//                (dir, name) -> dir.isDirectory() &&
-//                        (name.toLowerCase().endsWith(".zip") && name.toLowerCase().startsWith(getBackupFileNamePrefix())
-//                                || name.toLowerCase().endsWith(".kbi"))
-//        );
-
-//        Function<File, String> backupInformationProvider = file -> {
-//            Objects.requireNonNull(file);
-//            if (file.getName().toLowerCase().endsWith(".zip"))
-//                return getPrimitiveBackupInformationString(file.getName(), file.length());
-//                // TODO: refactor this to use {@link ObjectCollectionSerializer#fromDirectory}
-//            else if (file.getName().toLowerCase().endsWith(".kbi"))
-//                return getIncrementalBackupInformationString(file);
-//            return file.getName();
-//        };
 
         updateBackupList();
         synchronized (backupList) {
@@ -150,22 +131,6 @@ public final class KBCommands {
                 BackupInfo info = backupList.get(i);
                 printBackupInfo(context, info, i);
             }
-//            if (files != null) {
-//                if (files.length != 0) {
-//                    msgInfo(context, "Available backups: (file is not checked, manipulation may affect this plugin)");
-//                } else {
-//                    msgInfo(context, "There are no available backups. To make a new backup, run /kb backup.");
-//                }
-//                int i = 0;
-//                for (File file : files) {
-//                    ++i;
-//                    String backupFileName = file.getName();
-//                    msgInfo(context, String.format("[%d] %s", i, backupInformationProvider.apply(file)));
-//                    backupFileNameList.add(backupFileName);
-//                }
-//            } else {
-//                msgErr(context, "Error: failed to list files in backup folder.");
-//            }
         }
         return SUCCESS;
     }
@@ -230,21 +195,6 @@ public final class KBCommands {
     }
 
 
-//    public static int incrementalBackup(CommandContext<ServerCommandSource> context) {
-//        //KBMain.backup("name")
-//        String backupName = StringArgumentType.getString(context, "backupName");
-//        if (backupName.matches("[0-9]*")) {
-//            // Numeric param is not allowed
-//            backupName = String.format("a%s", backupName);
-//            msgWarn(context, String.format("Pure numeric name is not allowed. Renaming to %s", backupName));
-//        }
-//        return doBackup(context, backupName, IncrementalBackupMethod.getInstance());
-//    }
-//
-//    public static int incrementalBackupWithDefaultName(CommandContext<ServerCommandSource> context) {
-//        return doBackup(context, DEFAULT_BACKUP_NAME, IncrementalBackupMethod.getInstance());
-//    }
-
     /**
      * Delete an existing backup with context parameter backupName.
      * Simply set the pending backupName to given backupName, for the second confirmation.
@@ -390,7 +340,7 @@ public final class KBCommands {
         // By the way, update suggestion list.
         BackupNameSuggestionProvider.updateCandidateList();
 
-        return returnValue ? SUCCESS : FAILED; // block compiler's complain.
+        return returnValue ? SUCCESS : FAILED; // block compiler's complaint.
     }
 
     /**
@@ -401,7 +351,7 @@ public final class KBCommands {
      */
     public static int cancel(CommandContext<ServerCommandSource> context) {
         if (pendingOperation != null) {
-            PrintUtil.msgInfo(context, String.format("The %s has been cancelled.", pendingOperation.toString()), true);
+            PrintUtil.msgInfo(context, String.format("The %s has been cancelled.", pendingOperation), true);
             pendingOperation = null;
             return SUCCESS;
         } else {
@@ -422,22 +372,6 @@ public final class KBCommands {
         try {
             // List all backups
             updateBackupList();
-//            MinecraftServer server = context.getSource().getMinecraftServer();
-//            List<File> files = Arrays.asList(Objects.requireNonNull(getBackupSaveDirectory(server).listFiles()));
-//            files.removeIf(f -> !f.getName().startsWith(BackupFilesystemUtil.getBackupFileNamePrefix()));
-//            files.sort((x, y) -> (int) (BackupFilesystemUtil.getBackupTimeFromBackupFileName(y.getName()) - BackupFilesystemUtil.getBackupTimeFromBackupFileName(x.getName())));
-//            File prevBackupFile = files.get(0);
-//            String backupFileName = prevBackupFile.getName();
-//            int i;
-//            synchronized (backupList) {
-//                i = backupList.indexOf(backupFileName);
-//                if (i == -1) {
-//                    backupList.add(backupFileName);
-//                    i = backupList.size();
-//                } else {
-//                    ++i;
-//                }
-//            }
             synchronized (backupList) {
                 if (!backupList.isEmpty()) {
                     BackupInfo info = backupList.get(0);
@@ -454,47 +388,6 @@ public final class KBCommands {
         return SUCCESS;
     }
 
-//    private static String getPrimitiveBackupInformationString(String backupFileName, long backupFileSizeBytes) {
-//        return String.format(
-//                "(ZIP) %s , size: %s",
-//                PrimitiveBackupFileNameEncoder.INSTANCE.decode(backupFileName),
-//                getFriendlyFileSizeString(backupFileSizeBytes)
-//        );
-//    }
-
-//    private static String getIncrementalBackupInformationString(File backupFile) {
-//        try {
-//            SavedIncrementalBackup info = IncBackupInfoSerializer.fromFile(backupFile);
-//            return "(Incremental) " + info.getBackupName()
-//                    + ", " + DateUtil.getString(info.getBackupTime())
-//                    + ((info.getTotalSizeBytes() > 0) ?
-//                    (" size: " + BackupFilesystemUtil.getFriendlyFileSizeString(info.getTotalSizeBytes())) : "");
-//        } catch (IOException e) {
-//            e.printStackTrace();
-//            return "(Incremental) " + backupFile.getName();
-//        }
-//    }
-
-//    /**
-//     * Select the backup method we use.
-//     * @param context the context.
-//     * @return stat code.
-//     */
-//    public static int setMethod(CommandContext<ServerCommandSource> context) {
-//        String desiredMethodName = StringArgumentType.getString(context, "backupMethod");
-//        List<BackupType> backupMethods = Arrays.asList(BackupType.PRIMITIVE_ZIP_BACKUP, BackupType.OBJECT_TREE_BACKUP);
-//        for (BackupType method : backupMethods) {
-//            if(method.getName().equals(desiredMethodName)) {
-//                // Incremental backup
-////                activatedBackupMethod =
-//                msgInfo(context, String.format("Backup method is set to: %s", desiredMethodName));
-//                return SUCCESS;
-//            }
-//        }
-//
-//        return SUCCESS;
-//    }
-
 
     private static String parseBackupFileName(CommandContext<ServerCommandSource> context, String userInput) {
         try {
diff --git a/src/main/java/com/keuin/kbackupfabric/ui/PrimitiveBackupInfo.java b/src/main/java/com/keuin/kbackupfabric/ui/PrimitiveBackupInfo.java
index 1895647..e3a0060 100644
--- a/src/main/java/com/keuin/kbackupfabric/ui/PrimitiveBackupInfo.java
+++ b/src/main/java/com/keuin/kbackupfabric/ui/PrimitiveBackupInfo.java
@@ -38,11 +38,6 @@ public class PrimitiveBackupInfo implements BackupInfo {
 
     public static PrimitiveBackupInfo fromFile(File zipFile) {
         // TODO: fix this, use metadata file instead
-//        fileName = zipFile.getName();
-//        BackupFileNameEncoder.BackupBasicInformation info = PrimitiveBackupFileNameEncoder.INSTANCE.decode(fileName);
-//        if (info == null)
-//            throw new IllegalArgumentException("Invalid file name.");
-//        return new PrimitiveBackupInfo(info.customName, info.time, FilesystemUtil.getFileSizeBytes(zipFile));
         return new PrimitiveBackupInfo(zipFile.getName(), FilesystemUtil.getFileSizeBytes(zipFile));
     }
 
diff --git a/src/main/java/com/keuin/kbackupfabric/util/ReflectionUtils.java b/src/main/java/com/keuin/kbackupfabric/util/ReflectionUtils.java
index 2acc562..6fb1e3f 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/ReflectionUtils.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/ReflectionUtils.java
@@ -12,11 +12,7 @@ import java.lang.reflect.Method;
 public final class ReflectionUtils {
 
     /**
-     * 获取私有成员变量的值
-     *
-     * @param instance
-     * @param filedName
-     * @return
+     * Read private fields.
      */
     public static Object getPrivateField(Object instance, String filedName) throws NoSuchFieldException, IllegalAccessException {
         Field field = instance.getClass().getDeclaredField(filedName);
@@ -25,13 +21,7 @@ public final class ReflectionUtils {
     }
 
     /**
-     * 设置私有成员的值
-     *
-     * @param instance
-     * @param fieldName
-     * @param value
-     * @throws NoSuchFieldException
-     * @throws IllegalAccessException
+     * Modify private fields.
      */
     public static void setPrivateField(Object instance, String fieldName, Object value) throws NoSuchFieldException, IllegalAccessException {
         Field field = instance.getClass().getDeclaredField(fieldName);
@@ -40,18 +30,10 @@ public final class ReflectionUtils {
     }
 
     /**
-     * 访问私有方法
-     *
-     * @param instance
-     * @param methodName
-     * @param classes
-     * @param objects
-     * @return
-     * @throws NoSuchMethodException
-     * @throws InvocationTargetException
-     * @throws IllegalAccessException
+     * Call private methods.
      */
-    public static Object invokePrivateMethod(Object instance, String methodName, Class[] classes, String objects) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
+    public static Object invokePrivateMethod(Object instance, String methodName, Class<?>[] classes, String objects)
+            throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
         Method method = instance.getClass().getDeclaredMethod(methodName, classes);
         method.setAccessible(true);
         return method.invoke(instance, objects);
diff --git a/src/main/java/com/keuin/kbackupfabric/util/ZipUtil.java b/src/main/java/com/keuin/kbackupfabric/util/ZipUtil.java
index eea1148..ce14c8a 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/ZipUtil.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/ZipUtil.java
@@ -4,6 +4,7 @@ import com.keuin.kbackupfabric.exception.ZipUtilException;
 import com.keuin.kbackupfabric.metadata.BackupMetadata;
 
 import java.io.*;
+import java.nio.file.Files;
 import java.util.*;
 import java.util.zip.*;
 
@@ -46,7 +47,7 @@ public final class ZipUtil {
             ZipEntry entry = new ZipEntry(subPath);
             zipOutputStream.putNextEntry(entry);
 //            BufferedInputStream inputStream = new BufferedInputStream(new FileInputStream(file));
-            try (InputStream inputStream = new FileInputStream(file)) {
+            try (InputStream inputStream = Files.newInputStream(file.toPath())) {
                 while ((count = inputStream.read(buffer, 0, zipBufferSize)) != -1) {
                     zipOutputStream.write(buffer, 0, count);
                 }
@@ -100,7 +101,7 @@ public final class ZipUtil {
         File zipDir = new File(zipPath);
         if (!zipDir.exists() || !zipDir.isDirectory()) {
             if (!zipDir.mkdirs()) {
-                throw new IOException(String.format("Failed to make directory tree %s", zipDir.toString()));
+                throw new IOException(String.format("Failed to make directory tree %s", zipDir));
             }
         }
 
@@ -110,7 +111,7 @@ public final class ZipUtil {
         if (zipFile.exists()) {
             //删除已存在的目标文件
             if (!zipFile.delete()) {
-                throw new IOException(String.format("Failed to delete existing file %s", zipFile.toString()));
+                throw new IOException(String.format("Failed to delete existing file %s", zipFile));
             }
         }
 
@@ -175,7 +176,7 @@ public final class ZipUtil {
         File unzipFileDir = new File(unzipFilePath);
         if (!unzipFileDir.exists() || !unzipFileDir.isDirectory()) {
             if (!unzipFileDir.mkdirs())
-                throw new IOException(String.format("Failed to make directory tree %s", unzipFileDir.toString()));
+                throw new IOException(String.format("Failed to make directory tree %s", unzipFileDir));
         }
 
         // 开始解压
@@ -202,7 +203,7 @@ public final class ZipUtil {
                 // 如果文件夹路径不存在，则创建文件夹
                 if (!entryDir.exists() || !entryDir.isDirectory()) {
                     if (!entryDir.mkdirs())
-                        throw new IOException(String.format("Failed to make directory tree %s", entryDir.toString()));
+                        throw new IOException(String.format("Failed to make directory tree %s", entryDir));
                 }
 
                 // 创建解压文件
@@ -213,16 +214,16 @@ public final class ZipUtil {
                     securityManager.checkDelete(entryFilePath);
                     // 删除已存在的目标文件
                     if (!entryFile.delete())
-                        throw new IOException(String.format("Failed to delete existing file %s", entryFile.toString()));
+                        throw new IOException(String.format("Failed to delete existing file %s", entryFile));
                 }
                 if (entry.isDirectory()) {
                     // If the entry is a directory, we make its corresponding directory.
                     if (!entryFile.mkdir())
-                        throw new IOException(String.format("Failed to create directory %s", entryFile.toString()));
+                        throw new IOException(String.format("Failed to create directory %s", entryFile));
                 } else {
                     // Is a file, we write the data
                     // 写入文件
-                    try (OutputStream outputStream = new FileOutputStream(entryFile);
+                    try (OutputStream outputStream = Files.newOutputStream(entryFile.toPath());
                          InputStream inputStream = zip.getInputStream(entry)) {
                         while ((count = inputStream.read(buffer, 0, unzipBufferSize)) != -1) {
                             outputStream.write(buffer, 0, count);
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollection.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollection.java
index 0cd36a0..38b96ab 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollection.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollection.java
@@ -8,7 +8,7 @@ import java.util.*;
  * or it will not be compatible with old backups.
  * It remains only to keep a backward compatibility, and should be converted to `ObjectCollection2` as soon as possible.
  * Thus, this class is marked as `Depreciated`. However, it should not be removed since it is needed to read legacy
- * backups correctly. But new codes should not use this class any more.
+ * backups correctly. But new codes should not use this class anymore.
  */
 @Deprecated
 public class ObjectCollection implements Serializable {
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/Sha256Identifier.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/Sha256Identifier.java
index 31cde29..c640c0b 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/Sha256Identifier.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/Sha256Identifier.java
@@ -3,12 +3,11 @@ package com.keuin.kbackupfabric.util.backup.incremental.identifier;
 import com.keuin.kbackupfabric.util.BytesUtil;
 
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.IOException;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
 import java.util.Objects;
 
+import static com.keuin.kbackupfabric.backup.incremental.identifier.Sha256Identifier.sha256Hash;
+
 /**
  * Identifier based on sha256.
  * Immutable.
@@ -50,35 +49,7 @@ public class Sha256Identifier extends SingleHashIdentifier {
 
     @Override
     protected byte[] hash(File file) throws IOException {
-        try {
-            MessageDigest digest = MessageDigest.getInstance("SHA-256");
-
-            try (FileInputStream inputStream = new FileInputStream(file)) {
-                // This does not work. I don't know why
-//            FileChannel channel = inputStream.getChannel();
-//            ByteBuffer buffer = ByteBuffer.allocate(128);
-//            int readLength;
-//            while ((readLength = channel.read(buffer)) > 0)
-//                digest.update(buffer);
-
-                // This also works, without warnings
-                byte[] readBuffer = new byte[1024 * 1024];
-                int readLength;
-                while ((readLength = inputStream.read(readBuffer)) > 0)
-                    digest.update(readBuffer, 0, readLength);
-
-                // The below lines also works, but the IDE will complain about the while loop
-//            DigestInputStream digestInputStream = new DigestInputStream(inputStream, digest);
-//            while(digestInputStream.read() > 0)
-//                ;
-
-                return digest.digest();
-            }
-
-        } catch (NoSuchAlgorithmException ignored) {
-            // this shouldn't happen
-            return new byte[SHA256_LENGTH];
-        }
+        return sha256Hash(file);
     }
 
 }
\ No newline at end of file
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/SingleHashIdentifier.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/SingleHashIdentifier.java
index 6c67918..285c6ce 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/SingleHashIdentifier.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/SingleHashIdentifier.java
@@ -12,7 +12,6 @@ import java.util.Objects;
  * Immutable.
  */
 public abstract class SingleHashIdentifier implements ObjectIdentifier {
-
     private final byte[] hash;
     private final String type;
 
@@ -37,11 +36,11 @@ public abstract class SingleHashIdentifier implements ObjectIdentifier {
     }
 
     @Override
-    public boolean equals(Object obj) {
-        if (!(obj instanceof com.keuin.kbackupfabric.backup.incremental.identifier.SingleHashIdentifier)) {
-            return false;
-        }
-        return Arrays.equals(hash, ((SingleHashIdentifier) obj).hash);
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SingleHashIdentifier that = (SingleHashIdentifier) o;
+        return Arrays.equals(hash, that.hash) && type.equals(that.type);
     }
 
     @Override