diff --git a/sorm4j/src/main/java/org/nkjmlab/sorm4j/extension/h2/commands/ScriptSql.java b/sorm4j/src/main/java/org/nkjmlab/sorm4j/extension/h2/commands/ScriptSql.java
index eedf882d..0b691c23 100644
--- a/sorm4j/src/main/java/org/nkjmlab/sorm4j/extension/h2/commands/ScriptSql.java
+++ b/sorm4j/src/main/java/org/nkjmlab/sorm4j/extension/h2/commands/ScriptSql.java
@@ -118,11 +118,11 @@ public ScriptSql build() {
         }
       }
 
-      if (tables.size() != 0) {
+      if (!tables.isEmpty()) {
         ret.add("table");
         ret.add(String.join(",", tables));
       }
-      if (schemas.size() != 0) {
+      if (!schemas.isEmpty()) {
         ret.add("schema");
         ret.add(String.join(",", schemas));
       }
diff --git a/sorm4j/src/main/java/org/nkjmlab/sorm4j/internal/context/logging/LogContextImpl.java b/sorm4j/src/main/java/org/nkjmlab/sorm4j/internal/context/logging/LogContextImpl.java
index d3f9db1e..25b0bccc 100644
--- a/sorm4j/src/main/java/org/nkjmlab/sorm4j/internal/context/logging/LogContextImpl.java
+++ b/sorm4j/src/main/java/org/nkjmlab/sorm4j/internal/context/logging/LogContextImpl.java
@@ -25,7 +25,7 @@ public LogContextImpl(
       Supplier<SormLogger> loggerSupplier, Set<LogContext.Category> enabledCategories) {
     this.loggerSupplier = loggerSupplier != null ? loggerSupplier : getDefaultLoggerSupplier();
     this.enabledCategories =
-        enabledCategories.size() == 0 ? Collections.emptySet() : EnumSet.copyOf(enabledCategories);
+        enabledCategories.isEmpty() ? Collections.emptySet() : EnumSet.copyOf(enabledCategories);
   }
 
   public static Supplier<SormLogger> getDefaultLoggerSupplier() {
diff --git a/sorm4j/src/main/java/org/nkjmlab/sorm4j/table/definition/TableDefinition.java b/sorm4j/src/main/java/org/nkjmlab/sorm4j/table/definition/TableDefinition.java
index 9cee9b9a..192e5d6e 100644
--- a/sorm4j/src/main/java/org/nkjmlab/sorm4j/table/definition/TableDefinition.java
+++ b/sorm4j/src/main/java/org/nkjmlab/sorm4j/table/definition/TableDefinition.java
@@ -313,7 +313,7 @@ private static String createPrimaryKeyConstraint(String[] primaryKeys) {
     }
 
     private static String createUniqueConstraint(List<String[]> uniqueColumnPairs) {
-      return (uniqueColumnPairs == null || uniqueColumnPairs.size() == 0)
+      return (uniqueColumnPairs == null || uniqueColumnPairs.isEmpty())
           ? ""
           : ", "
               + String.join(
@@ -324,7 +324,7 @@ private static String createUniqueConstraint(List<String[]> uniqueColumnPairs) {
     }
 
     private static String createCheckConstraint(List<String> checkConditions) {
-      return (checkConditions == null || checkConditions.size() == 0)
+      return (checkConditions == null || checkConditions.isEmpty())
           ? ""
           : ", "
               + String.join(