diff --git a/src/chapter5/Example11.java b/src/chapter5/Example11.java
index e95df25..bfbc3ea 100644
--- a/src/chapter5/Example11.java
+++ b/src/chapter5/Example11.java
@@ -1,5 +1,9 @@
 package chapter5;
 
+/**
+ * 获取当前时间
+ */
+
 public class Example11 {
     public static void main(String[] args) {
         long startTime = System.currentTimeMillis();
diff --git a/src/chapter5/Example12.java b/src/chapter5/Example12.java
index bf30d61..cddc70a 100644
--- a/src/chapter5/Example12.java
+++ b/src/chapter5/Example12.java
@@ -3,6 +3,9 @@ package chapter5;
 import java.util.Enumeration;
 import java.util.Properties;
 
+/**
+ * 获取系统信息
+ */
 public class Example12 {
     public static void main(String[] args) {
         // 获取当前系统信息
@@ -15,3 +18,4 @@ public class Example12 {
         }
     }
 }
+