diff --git a/pom.xml b/pom.xml
index 36417c9..3a58532 100644
--- a/pom.xml
+++ b/pom.xml
@@ -10,6 +10,7 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <java.version>8</java.version>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
         <jackson.version>2.13.5</jackson.version>
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecord.java b/src/main/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecord.java
index 0ff178b..5c3ac3c 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecord.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecord.java
@@ -31,7 +31,8 @@ import xyz.zhouxy.plusone.commons.util.RegexUtil;
  * @author <a href="https://gitee.com/zhouxy108">ZhouXY</a>
  * @since 0.1.0
  */
-public abstract class ValidatableStringRecord {
+public abstract class ValidatableStringRecord
+        implements Comparable<ValidatableStringRecord> {
     private final String value;
 
     protected ValidatableStringRecord(String value, Pattern pattern) {
@@ -51,6 +52,11 @@ public abstract class ValidatableStringRecord {
         return this.value;
     }
 
+    @Override
+    public int compareTo(ValidatableStringRecord o) {
+        return this.value.compareTo(o.value);
+    }
+
     @Override
     public String toString() {
         return this.value();
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecordTests.java b/src/test/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecordTests.java
index a21170e..d2a6727 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecordTests.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/domain/ValidatableStringRecordTests.java
@@ -10,6 +10,11 @@ import xyz.zhouxy.plusone.commons.annotation.StaticFactoryMethod;
 import xyz.zhouxy.plusone.commons.annotation.ValueObject;
 import xyz.zhouxy.plusone.commons.constant.PatternConsts;
 
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
 class ValidatableStringRecordTests {
 
     private static final Logger log = LoggerFactory.getLogger(ValidatableStringRecordTests.class);
@@ -21,6 +26,16 @@ class ValidatableStringRecordTests {
         String usernameStr = username.value();
         assertNotNull(usernameStr);
         log.info("usernameStr: {}", usernameStr);
+
+        List<Username> usernames = Arrays.asList(
+                Username.of("ZhouXY108"),
+                Username.of("code_108"),
+                Username.of("Luquan"),
+                Username.of("Code108")
+        );
+        log.info("{}", Collections.max(usernames));
+        log.info("{}", Collections.max(usernames,
+                Comparator.<Username, String>comparing(o -> o.value().toLowerCase())));
     }
 }