diff --git a/binding/java/pom.xml b/binding/java/pom.xml
index aa8363f..a139f38 100644
--- a/binding/java/pom.xml
+++ b/binding/java/pom.xml
@@ -4,7 +4,7 @@
 
     <groupId>org.lionsoul</groupId>
     <artifactId>ip2region</artifactId>
-    <version>3.3.4</version>
+    <version>3.3.5</version>
     <packaging>jar</packaging>
 
     <name>ip2region</name>
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/service/ConfigBuilder.java b/binding/java/src/main/java/org/lionsoul/ip2region/service/ConfigBuilder.java
index 2f52c51..addaec9 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/service/ConfigBuilder.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/service/ConfigBuilder.java
@@ -49,16 +49,19 @@ public class ConfigBuilder {
     }
 
     public ConfigBuilder setXdbPath(String xdbPath) {
+        assert xdbPath != null && xdbPath.length() > 0;
         this.xdbPath = xdbPath;
         return this;
     }
 
     public ConfigBuilder setXdbFile(File xdbFile) {
+        assert xdbFile != null;
         this.xdbFile = xdbFile;
         return this;
     }
 
     public ConfigBuilder setXdbInputStream(InputStream xdbInputStream) {
+        assert xdbInputStream != null;
         this.xdbInputStream = xdbInputStream;
         return this;
     }