diff --git a/src/main/java/org/codelibs/fess/app/web/admin/searchlog/SearchForm.java b/src/main/java/org/codelibs/fess/app/web/admin/searchlog/SearchForm.java
index 2985b3e02..bdb01d6a3 100644
--- a/src/main/java/org/codelibs/fess/app/web/admin/searchlog/SearchForm.java
+++ b/src/main/java/org/codelibs/fess/app/web/admin/searchlog/SearchForm.java
@@ -45,12 +45,12 @@ public class SearchForm {
             return SearchLogPager.DEFAULT_PAGE_SIZE;
         }
         try {
-            int value = Integer.parseInt(size);
+            final int value = Integer.parseInt(size);
             if (value <= 0 || value > ComponentUtil.getFessConfig().getPageSearchlogMaxFetchSizeAsInteger()) {
                 return SearchLogPager.DEFAULT_PAGE_SIZE;
             }
             return value;
-        } catch (NumberFormatException e) {
+        } catch (final NumberFormatException e) {
             // ignore
             return SearchLogPager.DEFAULT_PAGE_SIZE;
         }
diff --git a/src/main/java/org/codelibs/fess/dict/DictionaryFile.java b/src/main/java/org/codelibs/fess/dict/DictionaryFile.java
index 5c0c18e2c..a3dd4822b 100644
--- a/src/main/java/org/codelibs/fess/dict/DictionaryFile.java
+++ b/src/main/java/org/codelibs/fess/dict/DictionaryFile.java
@@ -61,7 +61,7 @@ public abstract class DictionaryFile<T extends DictionaryItem> {
         return this;
     }
 
-    public void writeOut(WrittenStreamOut out) throws IOException {
+    public void writeOut(final WrittenStreamOut out) throws IOException {
         try (final CurlResponse curlResponse = dictionaryManager.getContentResponse(this);
                 final InputStream inputStream = new BufferedInputStream(curlResponse.getContentAsStream())) {
             out.write(inputStream);
diff --git a/src/main/java/org/codelibs/fess/dict/protwords/ProtwordsFile.java b/src/main/java/org/codelibs/fess/dict/protwords/ProtwordsFile.java
index c97643683..68897b923 100644
--- a/src/main/java/org/codelibs/fess/dict/protwords/ProtwordsFile.java
+++ b/src/main/java/org/codelibs/fess/dict/protwords/ProtwordsFile.java
@@ -134,7 +134,7 @@ public class ProtwordsFile extends DictionaryFile<ProtwordsItem> {
                 }
 
                 final String inputStrings = line;
-                String input = unescape(inputStrings);
+                final String input = unescape(inputStrings);
 
                 if (input.length() > 0) {
                     id++;
diff --git a/src/main/java/org/codelibs/fess/dict/stemmeroverride/StemmerOverrideFile.java b/src/main/java/org/codelibs/fess/dict/stemmeroverride/StemmerOverrideFile.java
index 7931740a6..d0068303a 100644
--- a/src/main/java/org/codelibs/fess/dict/stemmeroverride/StemmerOverrideFile.java
+++ b/src/main/java/org/codelibs/fess/dict/stemmeroverride/StemmerOverrideFile.java
@@ -155,8 +155,8 @@ public class StemmerOverrideFile extends DictionaryFile<StemmerOverrideItem> {
                     continue;
                 }
 
-                String input = m.group(1).trim();
-                String output = m.group(2).trim();
+                final String input = m.group(1).trim();
+                final String output = m.group(2).trim();
 
                 if (input == null || output == null) {
                     logger.warn("Failed to parse " + line + " in " + path);
diff --git a/src/main/java/org/codelibs/fess/dict/stemmeroverride/StemmerOverrideItem.java b/src/main/java/org/codelibs/fess/dict/stemmeroverride/StemmerOverrideItem.java
index 55a4f7b2e..1a401252b 100644
--- a/src/main/java/org/codelibs/fess/dict/stemmeroverride/StemmerOverrideItem.java
+++ b/src/main/java/org/codelibs/fess/dict/stemmeroverride/StemmerOverrideItem.java
@@ -81,24 +81,31 @@ public class StemmerOverrideItem extends DictionaryItem {
     }
 
     @Override
-    public boolean equals(Object obj) {
-        if (this == obj)
+    public boolean equals(final Object obj) {
+        if (this == obj) {
             return true;
-        if (obj == null)
+        }
+        if (obj == null) {
             return false;
-        if (getClass() != obj.getClass())
+        }
+        if (getClass() != obj.getClass()) {
             return false;
-        StemmerOverrideItem other = (StemmerOverrideItem) obj;
+        }
+        final StemmerOverrideItem other = (StemmerOverrideItem) obj;
         if (input == null) {
-            if (other.input != null)
+            if (other.input != null) {
                 return false;
-        } else if (!input.equals(other.input))
+            }
+        } else if (!input.equals(other.input)) {
             return false;
+        }
         if (output == null) {
-            if (other.output != null)
+            if (other.output != null) {
                 return false;
-        } else if (!output.equals(other.output))
+            }
+        } else if (!output.equals(other.output)) {
             return false;
+        }
         return true;
     }
 
diff --git a/src/main/java/org/codelibs/fess/dict/stopwords/StopwordsFile.java b/src/main/java/org/codelibs/fess/dict/stopwords/StopwordsFile.java
index 9b57712fb..cfeab1cb2 100644
--- a/src/main/java/org/codelibs/fess/dict/stopwords/StopwordsFile.java
+++ b/src/main/java/org/codelibs/fess/dict/stopwords/StopwordsFile.java
@@ -134,7 +134,7 @@ public class StopwordsFile extends DictionaryFile<StopwordsItem> {
                 }
 
                 final String inputStrings = line;
-                String input = unescape(inputStrings);
+                final String input = unescape(inputStrings);
 
                 if (input.length() > 0) {
                     id++;
diff --git a/src/main/java/org/codelibs/fess/es/client/FessEsClient.java b/src/main/java/org/codelibs/fess/es/client/FessEsClient.java
index 6a87af518..15de6f6b5 100644
--- a/src/main/java/org/codelibs/fess/es/client/FessEsClient.java
+++ b/src/main/java/org/codelibs/fess/es/client/FessEsClient.java
@@ -1175,7 +1175,7 @@ public class FessEsClient implements Client {
         T build(R response, H hit);
     }
 
-    public void setClusterName(String clusterName) {
+    public void setClusterName(final String clusterName) {
         this.clusterName = clusterName;
     }
 
@@ -1491,7 +1491,7 @@ public class FessEsClient implements Client {
     }
 
     @Override
-    public FieldCapabilitiesRequestBuilder prepareFieldCaps(String... indices) {
+    public FieldCapabilitiesRequestBuilder prepareFieldCaps(final String... indices) {
         return client.prepareFieldCaps(indices);
     }
 
diff --git a/src/main/java/org/codelibs/fess/es/config/exentity/CrawlingConfig.java b/src/main/java/org/codelibs/fess/es/config/exentity/CrawlingConfig.java
index e62cdf265..9f3ae0cfb 100644
--- a/src/main/java/org/codelibs/fess/es/config/exentity/CrawlingConfig.java
+++ b/src/main/java/org/codelibs/fess/es/config/exentity/CrawlingConfig.java
@@ -67,7 +67,7 @@ public interface CrawlingConfig {
     public enum ConfigType {
         WEB("W"), FILE("F"), DATA("D");
 
-        private String typePrefix;
+        private final String typePrefix;
 
         ConfigType(final String typePrefix) {
             this.typePrefix = typePrefix;
diff --git a/src/main/java/org/codelibs/fess/helper/PopularWordHelper.java b/src/main/java/org/codelibs/fess/helper/PopularWordHelper.java
index ec74e366b..ef8a1c8de 100644
--- a/src/main/java/org/codelibs/fess/helper/PopularWordHelper.java
+++ b/src/main/java/org/codelibs/fess/helper/PopularWordHelper.java
@@ -82,7 +82,7 @@ public class PopularWordHelper {
                         try {
                             popularWordsRequestBuilder.execute().getResponse().getItems().stream()
                                     .forEach(item -> wordList.add(item.getText()));
-                        } catch (SuggesterException e) {
+                        } catch (final SuggesterException e) {
                             logger.warn("Failed to generate popular words.", e);
                         }
 
diff --git a/src/main/java/org/codelibs/fess/helper/ViewHelper.java b/src/main/java/org/codelibs/fess/helper/ViewHelper.java
index dcbe653f1..bfc16c8c3 100644
--- a/src/main/java/org/codelibs/fess/helper/ViewHelper.java
+++ b/src/main/java/org/codelibs/fess/helper/ViewHelper.java
@@ -195,7 +195,7 @@ public class ViewHelper {
         final String escaped = LaFunctions.h(text);
         int pos = escaped.indexOf(escapedHighlightPre);
         while (pos >= 0) {
-            int c = escaped.codePointAt(pos);
+            final int c = escaped.codePointAt(pos);
             if (Character.isISOControl(c) || hihglightTerminalCharSet.contains(c)) {
                 break;
             }
diff --git a/src/main/java/org/codelibs/fess/thumbnail/ThumbnailManager.java b/src/main/java/org/codelibs/fess/thumbnail/ThumbnailManager.java
index bb6602677..3cabfd205 100644
--- a/src/main/java/org/codelibs/fess/thumbnail/ThumbnailManager.java
+++ b/src/main/java/org/codelibs/fess/thumbnail/ThumbnailManager.java
@@ -495,12 +495,12 @@ public class ThumbnailManager {
                     }
                     Files.move(path, newPath);
                     logger.info("Move " + path + " to " + newPath);
-                } catch (IOException e) {
+                } catch (final IOException e) {
                     logger.warn("Failed to move " + path, e);
                 }
             }
         }       );
-            } catch (IOException e) {
+            } catch (final IOException e) {
                 logger.warn("Failed to migrate thumbnail images.", e);
             }
         }, "ThumbnailMigrator").start();
diff --git a/src/main/java/org/codelibs/fess/util/QueryStringBuilder.java b/src/main/java/org/codelibs/fess/util/QueryStringBuilder.java
index ab93c3c1a..f27001200 100644
--- a/src/main/java/org/codelibs/fess/util/QueryStringBuilder.java
+++ b/src/main/java/org/codelibs/fess/util/QueryStringBuilder.java
@@ -81,7 +81,7 @@ public class QueryStringBuilder {
         return queryBuf.toString().trim();
     }
 
-    protected void appendQuery(final StringBuilder queryBuf, String q) {
+    protected void appendQuery(final StringBuilder queryBuf, final String q) {
         final boolean exists = q.indexOf(OR) != -1 || q.indexOf(OR_ALT) != -1;
         queryBuf.append(' ');
         if (exists) {