diff --git a/JavaCore/src/com/ddb/javacore/ood2/Human.java b/JavaCore/src/com/ddb/javacore/ood2/Human.java
index 77b9640..ef2bbac 100644
--- a/JavaCore/src/com/ddb/javacore/ood2/Human.java
+++ b/JavaCore/src/com/ddb/javacore/ood2/Human.java
@@ -16,7 +16,8 @@ public class Human implements Serializable, Comparable<Human> {
 	private String id;
 	private String name;
 
-	private Integer age;
+	private Integer age;	
+	//private transient Integer age;	//不进行序列化！
 	private String work;
 
 	public Human() {
@@ -41,7 +42,7 @@ public Human(String id, String name, Integer age, String work) {
 	 */
 	@Override
 	public String toString() {
-		return "Human [name=" + name + ", age=" + age + "]";
+		return "Human [id=" + id + ", age=" + age + "]";
 	}
 
 	public Human(String id, String name) {
diff --git a/JavaCore/src/com/ddb/javacore/ood6/Singleton.java b/JavaCore/src/com/ddb/javacore/ood6/Singleton.java
new file mode 100644
index 0000000..5bffdc7
--- /dev/null
+++ b/JavaCore/src/com/ddb/javacore/ood6/Singleton.java
@@ -0,0 +1,21 @@
+package com.ddb.javacore.ood6;
+
+public class Singleton {
+	// 3.用来存储当前类的一个实例、对象
+	//private static Singleton instance = null;	//懒汉式
+	private static Singleton instance = new Singleton();	//饿汉式
+
+	// 1.私有化构造方法
+	private Singleton() {
+		System.out.println("构造函数被执行....");
+	}
+
+	// 2.提供外部可以得到的对象实例的方法
+	public static Singleton getInstance() {
+		if (instance == null) {
+			instance = new Singleton();
+		}
+		return instance;
+	}
+
+}
diff --git a/JavaCore/src/com/ddb/javacore/ood6/TestSingleton.java b/JavaCore/src/com/ddb/javacore/ood6/TestSingleton.java
new file mode 100644
index 0000000..f6378c3
--- /dev/null
+++ b/JavaCore/src/com/ddb/javacore/ood6/TestSingleton.java
@@ -0,0 +1,18 @@
+package com.ddb.javacore.ood6;
+
+public class TestSingleton {
+
+	public static void main(String[] args) {
+		Singleton singleton1 =Singleton.getInstance();
+		Singleton singleton2 =Singleton.getInstance();
+		Singleton singleton3 =Singleton.getInstance();
+		Singleton singleton4 =Singleton.getInstance();
+
+		System.out.println(singleton1);
+		System.out.println(singleton2);
+		System.out.println(singleton3);
+		System.out.println(singleton4);
+		//System.out.println(Singleton.instance);
+	}
+
+}