diff --git a/README.md b/README.md
index 66d1d5e..96a2869 100644
--- a/README.md
+++ b/README.md
@@ -9,11 +9,10 @@ Several [bundle applications](#bundle-apps) using this framework are also availa
 
 ## Requirements
 
-- **Running**: Java 11 or later
+- **Running**: Java 17 or later
 - **Building**: Java 17 or later (required by Gradle 9)
 
-> **Note**: This is the last release supporting Java 11 as a runtime target.
-> Future versions will require Java 17 or later.
+> To run on Java 11, use the pre-built JAR from [v0.7.0](https://github.com/sh5i/git-stein/releases/tag/v0.7.0).
 
 
 ## Build and Run
diff --git a/build.gradle b/build.gradle
index 09e8d75..49be582 100644
--- a/build.gradle
+++ b/build.gradle
@@ -17,29 +17,14 @@ java {
         // v61 (Java 17, LTS)
         // v65 (Java 21, LTS)
         // v69 (Java 25, LTS)
-        languageVersion = JavaLanguageVersion.of(11)
+        languageVersion = JavaLanguageVersion.of(17)
     }
 }
 
 dependencies {
-    // jgit 7.x requires Java 17; staying on 6.x for Java 11 compatibility
-    api 'org.eclipse.jgit:org.eclipse.jgit:6.10.1.202505221210-r'
-
-    // JDT 3.29+ and eclipse platform require Java 17; staying on 3.28.x for Java 11 compatibility
-    implementation 'org.eclipse.jdt:org.eclipse.jdt.core:3.28.0'
-    implementation 'org.eclipse.platform:org.eclipse.core.commands:3.8.0'
-    implementation 'org.eclipse.platform:org.eclipse.core.contenttype:3.5.100'
-    implementation 'org.eclipse.platform:org.eclipse.core.expressions:3.5.100'
-    implementation 'org.eclipse.platform:org.eclipse.core.filesystem:1.7.0'
-    implementation 'org.eclipse.platform:org.eclipse.core.jobs:3.8.0'
-    implementation 'org.eclipse.platform:org.eclipse.core.resources:3.14.0'
-    implementation 'org.eclipse.platform:org.eclipse.core.runtime:3.13.0'
-    implementation 'org.eclipse.platform:org.eclipse.equinox.app:1.3.400'
-    implementation 'org.eclipse.platform:org.eclipse.equinox.common:3.8.0'
-    implementation 'org.eclipse.platform:org.eclipse.equinox.preferences:3.6.1'
-    implementation 'org.eclipse.platform:org.eclipse.equinox.registry:3.6.100'
-    implementation 'org.eclipse.platform:org.eclipse.osgi:3.11.2'
-    implementation 'org.eclipse.platform:org.eclipse.text:3.6.0'
+    api 'org.eclipse.jgit:org.eclipse.jgit:7.6.0.202603022253-r'
+
+    implementation 'org.eclipse.jdt:org.eclipse.jdt.core:3.45.0'
 
     implementation 'org.slf4j:slf4j-api:2.0.17'
     implementation 'ch.qos.logback:logback-classic:1.5.32'
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 1b33c55..61285a6 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 37f78a6..c61a118 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-9.3.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.4.1-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
diff --git a/gradlew b/gradlew
index 23d15a9..adff685 100755
--- a/gradlew
+++ b/gradlew
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 #
-# Copyright © 2015-2021 the original authors.
+# Copyright © 2015 the original authors.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -114,7 +114,6 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -172,7 +171,6 @@ fi
 # For Cygwin or MSYS, switch paths to Windows format before running java
 if "$cygwin" || "$msys" ; then
     APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
-    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
 
     JAVACMD=$( cygpath --unix "$JAVACMD" )
 
@@ -212,7 +210,6 @@ DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
-        -classpath "$CLASSPATH" \
         -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
         "$@"
 
diff --git a/gradlew.bat b/gradlew.bat
index 5eed7ee..e509b2d 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -70,11 +70,10 @@ goto fail
 :execute
 @rem Setup the command line
 
-set CLASSPATH=
 
 
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
 
 :end
 @rem End local scope for the variables with windows NT shell
diff --git a/src/main/java/jp/ac/titech/c/se/stein/Application.java b/src/main/java/jp/ac/titech/c/se/stein/Application.java
index 15eb759..bf956b2 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/Application.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/Application.java
@@ -274,8 +274,8 @@ public int execute(final ParseResult parseResult) throws ExecutionException, Par
         // help
         if (parseResult.subcommands().size() >= 2) {
             final Object cmd = parseResult.subcommands().get(0).commandSpec().userObject();
-            if (cmd instanceof SettableHelpCommand) {
-                ((SettableHelpCommand) cmd).setCommand(parseResult.subcommands().get(1).commandSpec().name());
+            if (cmd instanceof SettableHelpCommand shc) {
+                shc.setCommand(parseResult.subcommands().get(1).commandSpec().name());
             }
         }
         if (CommandLine.printHelpIfRequested(parseResult)) {
@@ -310,8 +310,8 @@ public List<RewriterCommand> optimizeRewriters(final List<RewriterCommand> comma
         final List<BlobTranslator> pending = new ArrayList<>();
 
         for (final RewriterCommand cmd : commands) {
-            if (cmd instanceof BlobTranslator) {
-                pending.add((BlobTranslator) cmd);
+            if (cmd instanceof BlobTranslator t) {
+                pending.add(t);
             } else {
                 flushPendingTranslators(pending, result);
                 result.add(cmd);
diff --git a/src/main/java/jp/ac/titech/c/se/stein/app/Anonymize.java b/src/main/java/jp/ac/titech/c/se/stein/app/Anonymize.java
index ad906ae..a113e01 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/app/Anonymize.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/app/Anonymize.java
@@ -126,8 +126,7 @@ public AnyHotEntry rewriteBlobEntry(BlobEntry entry, final Context c) {
     @Override
     protected AnyColdEntry rewriteTreeEntry(TreeEntry entry, Context c) {
         final AnyColdEntry result = super.rewriteTreeEntry(entry, c);
-        if (isTreeNameEnabled && result instanceof Entry) {
-            final Entry e = (Entry) result;
+        if (isTreeNameEnabled && result instanceof Entry e) {
             return Entry.of(e.mode, treeNameMap.convert(e.name), e.id, e.directory);
         }
         return result;
diff --git a/src/main/java/jp/ac/titech/c/se/stein/app/blob/Cregit.java b/src/main/java/jp/ac/titech/c/se/stein/app/blob/Cregit.java
index 5decb18..250a9b4 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/app/blob/Cregit.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/app/blob/Cregit.java
@@ -62,20 +62,11 @@ protected void setLanguage(final String language) {
         this.language = language;
         if (filter.isDefault()) {
             switch (language) {
-                case "C":
-                    filter.setPatterns(C_EXT);
-                    break;
-                case "C++":
-                    filter.setPatterns(CXX_EXT);
-                    break;
-                case "C#":
-                    filter.setPatterns(CSHARP_EXT);
-                    break;
-                case "Java":
-                    filter.setPatterns(JAVA_EXT);
-                    break;
-                default:
-                    log.error("Unknown language: {}", language);
+                case "C" -> filter.setPatterns(C_EXT);
+                case "C++" -> filter.setPatterns(CXX_EXT);
+                case "C#" -> filter.setPatterns(CSHARP_EXT);
+                case "Java" -> filter.setPatterns(JAVA_EXT);
+                default -> log.error("Unknown language: {}", language);
             }
         }
     }
diff --git a/src/main/java/jp/ac/titech/c/se/stein/app/blob/FilterBlob.java b/src/main/java/jp/ac/titech/c/se/stein/app/blob/FilterBlob.java
index 4da0153..17cad4b 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/app/blob/FilterBlob.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/app/blob/FilterBlob.java
@@ -61,18 +61,13 @@ public Long convert(final String value) {
             final int len = value.length();
             final char unit = Character.toUpperCase(value.charAt(len - 1));
             final String num = value.substring(0, len - 1);
-            switch (unit) {
-                case 'B':
-                    return convert(num);
-                case 'K':
-                    return displaySizeToByteCount(num, 1024);
-                case 'M':
-                    return displaySizeToByteCount(num, 1024 * 1024);
-                case 'G':
-                    return displaySizeToByteCount(num, 1024 * 1024 * 1024);
-                default:
-                    return displaySizeToByteCount(value, 1);
-            }
+            return switch (unit) {
+                case 'B' -> convert(num);
+                case 'K' -> displaySizeToByteCount(num, 1024);
+                case 'M' -> displaySizeToByteCount(num, 1024 * 1024);
+                case 'G' -> displaySizeToByteCount(num, 1024 * 1024 * 1024);
+                default -> displaySizeToByteCount(value, 1);
+            };
         }
 
         protected long displaySizeToByteCount(final String value, final long base) {
diff --git a/src/main/java/jp/ac/titech/c/se/stein/app/blob/HistorageViaJDT.java b/src/main/java/jp/ac/titech/c/se/stein/app/blob/HistorageViaJDT.java
index 1f862b1..889a622 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/app/blob/HistorageViaJDT.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/app/blob/HistorageViaJDT.java
@@ -159,8 +159,8 @@ public ClassModule(final String name, final Module parent, final String content,
 
         @Override
         public String getBasename() {
-            if (parent instanceof ClassModule) {
-                return parent.getBasename() + "." + name;
+            if (parent instanceof ClassModule cm) {
+                return cm.getBasename() + "." + name;
             } else {
                 return parent.getBasename().equals(name) ? name : name + "[" + parent.getBasename() + "]";
             }
@@ -300,8 +300,7 @@ protected CompilationUnit parse() {
          * Creates a JDT ASTParser.
          */
         protected ASTParser createParser() {
-            final ASTParser parser = ASTParser.newParser(AST.JLS17);
-            @SuppressWarnings("unchecked")
+            final ASTParser parser = ASTParser.newParser(AST.JLS25);
             final Map<String, String> options = DefaultCodeFormatterConstants.getEclipseDefaultSettings();
             options.put(JavaCore.COMPILER_COMPLIANCE, JavaCore.VERSION_17);
             options.put(JavaCore.COMPILER_CODEGEN_TARGET_PLATFORM, JavaCore.VERSION_17);
diff --git a/src/main/java/jp/ac/titech/c/se/stein/app/blob/TokenizeViaJDT.java b/src/main/java/jp/ac/titech/c/se/stein/app/blob/TokenizeViaJDT.java
index 34c52ba..7672b36 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/app/blob/TokenizeViaJDT.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/app/blob/TokenizeViaJDT.java
@@ -39,7 +39,7 @@ public AnyHotEntry rewriteBlobEntry(final BlobEntry entry, final Context c) {
      * Encodes the given source to linetoken format.
      */
     public static String encode(final String source) {
-        final IScanner scanner = ToolFactory.createScanner(true, true, false, JavaCore.VERSION_17);
+        final IScanner scanner = ToolFactory.createScanner(true, true, false, JavaCore.VERSION_25);
         scanner.setSource(source.toCharArray());
         final StringBuilder buffer = new StringBuilder();
         try {
diff --git a/src/main/java/jp/ac/titech/c/se/stein/core/Context.java b/src/main/java/jp/ac/titech/c/se/stein/core/Context.java
index 2af2465..86388b9 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/core/Context.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/core/Context.java
@@ -101,20 +101,14 @@ protected String entryToString(final Map.Entry<Key, Object> e) {
     }
 
     protected static String getStringValue(final Key key, final Object value) {
-        switch (key) {
-        case commit:
-            return ((RevCommit) value).name();
-        case path:
-            return '"' + (String) value + '"';
-        case entry:
-            return value.toString();
-        case tag:
-            return ((RevTag) value).name();
-        case ref:
-            return ((Ref) value).getName();
-        default:
-            return null;
-        }
+        return switch (key) {
+            case commit -> ((RevCommit) value).name();
+            case path -> '"' + (String) value + '"';
+            case entry -> value.toString();
+            case tag -> ((RevTag) value).name();
+            case ref -> ((Ref) value).getName();
+            default -> null;
+        };
     }
 
     @Override
diff --git a/src/main/java/jp/ac/titech/c/se/stein/core/RepositoryAccess.java b/src/main/java/jp/ac/titech/c/se/stein/core/RepositoryAccess.java
index 7be85c7..a568cd1 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/core/RepositoryAccess.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/core/RepositoryAccess.java
@@ -1,6 +1,5 @@
 package jp.ac.titech.c.se.stein.core;
 
-import java.io.File;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -298,17 +297,11 @@ public ObjectId writeBlob(final byte[] data, final Context writingContext) {
     public ObjectId copyTree(final ObjectId treeId, final RepositoryAccess target, final Context c) {
         final List<Entry> entries = new ArrayList<>();
         for (final Entry e : readTree(treeId, null)) {
-            switch (e.getType()) {
-                case TREE:
-                    entries.add(Entry.of(e.getMode(), e.getName(), copyTree(e.getId(), target, c)));
-                    break;
-                case BLOB:
-                    entries.add(Entry.of(e.getMode(), e.getName(), copyBlob(e.getId(), target, c)));
-                    break;
-                default:
-                    entries.add(e);
-                    break;
-            }
+            entries.add(switch (e.getType()) {
+                case tree -> Entry.of(e.getMode(), e.getName(), copyTree(e.getId(), target, c));
+                case blob -> Entry.of(e.getMode(), e.getName(), copyBlob(e.getId(), target, c));
+                default -> e;
+            });
         }
         return target.writeTree(entries, c);
     }
diff --git a/src/main/java/jp/ac/titech/c/se/stein/entry/AnyColdEntry.java b/src/main/java/jp/ac/titech/c/se/stein/entry/AnyColdEntry.java
index 4bde10a..5254ddb 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/entry/AnyColdEntry.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/entry/AnyColdEntry.java
@@ -102,14 +102,11 @@ public String toString() {
 
         @Override
         public AnyColdEntry normalize() {
-            switch (size()) {
-                case 0:
-                    return empty();
-                case 1:
-                    return entries.get(0);
-                default:
-                    return this;
-            }
+            return switch (size()) {
+                case 0 -> empty();
+                case 1 -> entries.get(0);
+                default -> this;
+            };
         }
     }
 
diff --git a/src/main/java/jp/ac/titech/c/se/stein/entry/BlobEntry.java b/src/main/java/jp/ac/titech/c/se/stein/entry/BlobEntry.java
index cbc00ca..965ced6 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/entry/BlobEntry.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/entry/BlobEntry.java
@@ -18,7 +18,7 @@
  * @see SourceBlob
  * @see NewBlob
  */
-public abstract class BlobEntry extends HotEntry {
+public abstract sealed class BlobEntry extends HotEntry permits BlobEntry.SourceBlob, BlobEntry.NewBlob {
     public abstract byte[] getBlob();
 
     /**
@@ -61,7 +61,7 @@ public NewBlob update(final String newContent) {
      * The blob content is lazily loaded on the first call to {@link #getBlob()}.
      */
     @RequiredArgsConstructor(access = AccessLevel.PACKAGE)
-    public static class SourceBlob extends BlobEntry {
+    public static final class SourceBlob extends BlobEntry {
         @Delegate(types = SingleEntry.class)
         private final Entry entry;
 
@@ -93,7 +93,7 @@ public String toString() {
      */
     @Slf4j
     @RequiredArgsConstructor(access = AccessLevel.PACKAGE)
-    public static class NewBlob extends BlobEntry {
+    public static final class NewBlob extends BlobEntry {
         @Getter
         private final int mode;
 
diff --git a/src/main/java/jp/ac/titech/c/se/stein/entry/HotEntry.java b/src/main/java/jp/ac/titech/c/se/stein/entry/HotEntry.java
index 21689c7..d35b1f0 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/entry/HotEntry.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/entry/HotEntry.java
@@ -18,7 +18,7 @@
  * @see TreeEntry
  * @see Entry
  */
-public abstract class HotEntry implements AnyHotEntry, SingleEntry {
+public abstract sealed class HotEntry implements AnyHotEntry, SingleEntry permits BlobEntry, TreeEntry {
     /**
      * Creates a {@link BlobEntry} that lazily reads blob content from the given source.
      */
diff --git a/src/main/java/jp/ac/titech/c/se/stein/entry/SingleEntry.java b/src/main/java/jp/ac/titech/c/se/stein/entry/SingleEntry.java
index 1b63591..9c5f377 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/entry/SingleEntry.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/entry/SingleEntry.java
@@ -14,7 +14,7 @@ public interface SingleEntry extends Comparable<SingleEntry> {
      * The kind of object an entry refers to.
      */
     enum Type {
-        BLOB, TREE, LINK
+        blob, tree, link
     }
 
     /**
@@ -70,11 +70,11 @@ default boolean isBlob() {
      */
     default Type getType() {
         if (isTree()) {
-            return Type.TREE;
+            return Type.tree;
         } else if (isLink()) {
-            return Type.LINK;
+            return Type.link;
         } else {
-            return Type.BLOB;
+            return Type.blob;
         }
     }
 
diff --git a/src/main/java/jp/ac/titech/c/se/stein/entry/TreeEntry.java b/src/main/java/jp/ac/titech/c/se/stein/entry/TreeEntry.java
index fb267fd..7a74cfe 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/entry/TreeEntry.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/entry/TreeEntry.java
@@ -19,7 +19,7 @@
  * @see SourceTree
  * @see NewTree
  */
-public abstract class TreeEntry extends HotEntry {
+public abstract sealed class TreeEntry extends HotEntry permits TreeEntry.SourceTree, TreeEntry.NewTree {
     @Override
     public int getMode() {
         return FileMode.TREE.getBits();
@@ -53,7 +53,7 @@ public NewTree update(List<HotEntry> newChildren) {
      * A Hot tree entry backed by an existing tree in a repository.
      * The tree contents are lazily loaded on the first call to {@link #getEntries()}.
      */
-    public static class SourceTree extends TreeEntry {
+    public static final class SourceTree extends TreeEntry {
         @Delegate(types = SingleEntry.class)
         private final Entry entry;
 
@@ -106,7 +106,7 @@ public String toString() {
      * On {@link #fold}, children are recursively folded and an empty tree
      * (all children produce zero IDs) collapses to a zero-ID entry.</p>
      */
-    public static class NewTree extends TreeEntry {
+    public static final class NewTree extends TreeEntry {
         @Getter
         private final String name;
         @Getter
diff --git a/src/main/java/jp/ac/titech/c/se/stein/rewriter/BlobTranslator.java b/src/main/java/jp/ac/titech/c/se/stein/rewriter/BlobTranslator.java
index ed995f6..9eceeef 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/rewriter/BlobTranslator.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/rewriter/BlobTranslator.java
@@ -69,14 +69,13 @@ public AnyHotEntry rewriteBlobEntry(final BlobEntry entry, final Context c) {
         }
 
         private AnyHotEntry apply(AnyHotEntry input, List<BlobTranslator> rest, Context c) {
-            if (input instanceof BlobEntry) {
+            if (input instanceof BlobEntry blob) {
                 final BlobTranslator head = rest.get(0);
                 final List<BlobTranslator> tail = rest.subList(1, rest.size());
-                final AnyHotEntry result = head.rewriteBlobEntry((BlobEntry) input, c);
+                final AnyHotEntry result = head.rewriteBlobEntry(blob, c);
                 return tail.isEmpty() ? result : apply(result, tail, c);
             }
-            if (input instanceof TreeEntry) {
-                final TreeEntry tree = (TreeEntry) input;
+            if (input instanceof TreeEntry tree) {
                 final List<HotEntry> newChildren = tree.getHotEntries().stream()
                         .flatMap(e -> apply(e, rest, c).stream())
                         .collect(Collectors.toList());
diff --git a/src/main/java/jp/ac/titech/c/se/stein/rewriter/RepositoryRewriter.java b/src/main/java/jp/ac/titech/c/se/stein/rewriter/RepositoryRewriter.java
index a681b3e..02c5b5c 100644
--- a/src/main/java/jp/ac/titech/c/se/stein/rewriter/RepositoryRewriter.java
+++ b/src/main/java/jp/ac/titech/c/se/stein/rewriter/RepositoryRewriter.java
@@ -346,25 +346,17 @@ protected AnyColdEntry getEntry(final Entry entry, final Context c) {
      */
     protected AnyColdEntry rewriteEntry(final Entry entry, final Context c) {
         final Context uc = c.with(Key.entry, entry);
-        switch (entry.getType()) {
-            case BLOB:
-                final AnyColdEntry newBlob = rewriteBlobEntry(HotEntry.of(entry, source), uc).fold(target, uc);
-                log.debug("Rewrite blob: {} -> {} {}", entry, newBlob, c);
-                return newBlob;
-            case TREE:
+        final AnyColdEntry result = switch (entry.getType()) {
+            case blob -> rewriteBlobEntry(HotEntry.of(entry, source), uc).fold(target, uc);
+            case tree -> {
                 final String path = entry.isRoot() ? "" : c.getPath() + "/" + entry.name;
                 final String dir = isPathSensitive ? path : null;
-                final AnyColdEntry newTree = rewriteTreeEntry(HotEntry.ofTree(entry, source, dir), uc.with(Key.path, path));
-                log.debug("Rewrite tree: {} -> {} {}", entry, newTree, c);
-                return newTree;
-            case LINK:
-                final AnyColdEntry newLink = rewriteLinkEntry(entry, uc);
-                log.debug("Rewrite link: {} -> {} {}", entry, newLink, c);
-                return newLink;
-            default:
-                assert false;
-                return null;
-        }
+                yield rewriteTreeEntry(HotEntry.ofTree(entry, source, dir), uc.with(Key.path, path));
+            }
+            case link -> rewriteLinkEntry(entry, uc);
+        };
+        log.debug("Rewrite {}: {} -> {} {}", entry.getType(), entry, result, c);
+        return result;
     }
 
     protected AnyHotEntry rewriteBlobEntry(BlobEntry entry, Context c) {
@@ -529,36 +521,36 @@ protected RefEntry rewriteRefEntry(final RefEntry entry, final Context c) {
      * Rewrites the referred object by a ref or a tag.
      */
     protected ObjectId rewriteRefObject(final ObjectId id, final int type, final Context c) {
-        switch (type) {
-            case Constants.OBJ_COMMIT: // 1: commit
+        return switch (type) {
+            case Constants.OBJ_COMMIT -> {
                 final ObjectId newCommitId = commitMapping.get(id);
                 if (newCommitId == null) {
                     log.warn("Rewritten commit not found: {} {}", id.name(), c);
-                    return id;
+                    yield id;
                 }
-                return newCommitId;
-
-            case Constants.OBJ_TREE: // 2: tree
+                yield newCommitId;
+            }
+            case Constants.OBJ_TREE -> {
                 // TODO rewriting opportunity for this tree
                 final ObjectId newTreeId = source.copyTree(id, target, c);
                 log.warn("A ref object tree {} found, just copied {}", id.name(), c);
-                return newTreeId;
-
-            case Constants.OBJ_BLOB: // 3: blob
+                yield newTreeId;
+            }
+            case Constants.OBJ_BLOB -> {
                 // TODO rewriting opportunity for this blob
                 final ObjectId newBlobId = source.copyBlob(id, target, c);
                 log.warn("A ref object blob {} found, just copied {}", id.name(), c);
-                return newBlobId;
-
-            case Constants.OBJ_TAG: // 4: tag
+                yield newBlobId;
+            }
+            case Constants.OBJ_TAG -> {
                 final ObjectId newTagId = tagMapping.get(id);
-                return newTagId != null ? newTagId : rewriteTag(source.parseTag(id), c);
-
-            default:
-                // referring non-commit and non-tag; ignore it
+                yield newTagId != null ? newTagId : rewriteTag(source.parseTag(id), c);
+            }
+            default -> {
                 log.warn("Ignore unknown type ({}): {} {}", type, id.name(), c);
-                return id;
-        }
+                yield id;
+            }
+        };
     }
 
     /**
diff --git a/src/test/java/jp/ac/titech/c/se/stein/entry/EntryTest.java b/src/test/java/jp/ac/titech/c/se/stein/entry/EntryTest.java
index 1999e22..22c68cc 100644
--- a/src/test/java/jp/ac/titech/c/se/stein/entry/EntryTest.java
+++ b/src/test/java/jp/ac/titech/c/se/stein/entry/EntryTest.java
@@ -36,17 +36,17 @@ public void testType() {
         assertTrue(blob.isBlob());
         assertFalse(blob.isTree());
         assertFalse(blob.isLink());
-        assertEquals(SingleEntry.Type.BLOB, blob.getType());
+        assertEquals(SingleEntry.Type.blob, blob.getType());
 
         assertTrue(tree.isTree());
         assertFalse(tree.isBlob());
         assertFalse(tree.isLink());
-        assertEquals(SingleEntry.Type.TREE, tree.getType());
+        assertEquals(SingleEntry.Type.tree, tree.getType());
 
         assertTrue(link.isLink());
         assertFalse(link.isBlob());
         assertFalse(link.isTree());
-        assertEquals(SingleEntry.Type.LINK, link.getType());
+        assertEquals(SingleEntry.Type.link, link.getType());
     }
 
     @Test
diff --git a/src/test/java/jp/ac/titech/c/se/stein/entry/HotEntryTest.java b/src/test/java/jp/ac/titech/c/se/stein/entry/HotEntryTest.java
index 4714651..3f52f45 100644
--- a/src/test/java/jp/ac/titech/c/se/stein/entry/HotEntryTest.java
+++ b/src/test/java/jp/ac/titech/c/se/stein/entry/HotEntryTest.java
@@ -41,7 +41,7 @@ public void testSingleEntryMethods() {
         final BlobEntry withDir = HotEntry.of(BLOB_MODE, "hello", HELLO, "src");
         assertEquals("src/hello", withDir.getPath());
         assertTrue(withDir.isBlob());
-        assertEquals(SingleEntry.Type.BLOB, withDir.getType());
+        assertEquals(SingleEntry.Type.blob, withDir.getType());
     }
 
     @Test