diff --git a/src/main/java/alibaba/java/ParentClass.java b/src/main/java/alibaba/java/ParentClass.java
index 4c2379b..4797f92 100644
--- a/src/main/java/alibaba/java/ParentClass.java
+++ b/src/main/java/alibaba/java/ParentClass.java
@@ -1,8 +1,14 @@
 package alibaba.java;
 
-public class ParentClass {
+class ParentClass {
     public String name = "parent";
-    
+}
+
+class SonClass extends ParentClass {
+    public String name = "son";
+}
+
+public class Driver{
     public static void main(String[] args) {
         ParentClass parentClass = new SonClass();
         SonClass sonClass = new SonClass();
@@ -12,7 +18,3 @@ public static void main(String[] args) {
         System.out.println("debug...");
     }
 }
-
-class SonClass extends ParentClass {
-    public String name = "son";
-}