diff --git a/src/chapter6/Example21.java b/src/chapter6/Example21.java
index dafc24b..524e3a6 100644
--- a/src/chapter6/Example21.java
+++ b/src/chapter6/Example21.java
@@ -1,4 +1,20 @@
 package chapter6;
 
+import java.util.Enumeration;
+import java.util.Properties;
+
 public class Example21 {
+    public static void main(String[] args) {
+        Properties p = new Properties();
+        p.setProperty("Backgroudnd", "red");
+        p.setProperty("Font-size", "14px");
+        p.setProperty("Language", "Chinese");
+
+        Enumeration names = p.propertyNames();
+        while (names.hasMoreElements()) {
+            String key = (String) names.nextElement();
+            String value = p.getProperty(key);
+            System.out.println(key + "=" + value);
+        }
+    }
 }