diff --git a/notes/pics/dp-iterator.png b/notes/pics/dp-iterator.png
index 6ff07af7..8a53de59 100644
Binary files a/notes/pics/dp-iterator.png and b/notes/pics/dp-iterator.png differ
diff --git a/notes/设计模式 - 迭代器.md b/notes/设计模式 - 迭代器.md
index 1d1ecbc4..ec2c294d 100644
--- a/notes/设计模式 - 迭代器.md	
+++ b/notes/设计模式 - 迭代器.md	
@@ -12,13 +12,13 @@
 
 ### 实现
 ```java
-public interface Aggregate {
-    Iterator createIterator();
+public interface Aggregate<Item> {
+    Iterator<Item> createIterator();
 }
 ```
 
 ```java
-public class ConcreteAggregate implements Aggregate {
+public class ConcreteAggregate implements Aggregate<Integer> {
 
     private Integer[] items;
 
@@ -30,8 +30,8 @@ public class ConcreteAggregate implements Aggregate {
     }
 
     @Override
-    public Iterator createIterator() {
-        return new ConcreteIterator<Integer>(items);
+    public Iterator<Integer> createIterator() {
+        return new ConcreteIterator<>(items);
     }
 }
 ```
@@ -46,7 +46,7 @@ public interface Iterator<Item> {
 ```
 
 ```java
-public class ConcreteIterator<Item> implements Iterator {
+public class ConcreteIterator<Item> implements Iterator<Item> {
 
     private Item[] items;
     private int position = 0;
@@ -56,7 +56,7 @@ public class ConcreteIterator<Item> implements Iterator {
     }
 
     @Override
-    public Object next() {
+    public Item next() {
         return items[position++];
     }
 
@@ -71,7 +71,7 @@ public class ConcreteIterator<Item> implements Iterator {
 public class Client {
 
     public static void main(String[] args) {
-        Aggregate aggregate = new ConcreteAggregate();
+        Aggregate<Integer> aggregate = new ConcreteAggregate();
         Iterator<Integer> iterator = aggregate.createIterator();
         while (iterator.hasNext()) {
             System.out.println(iterator.next());
@@ -80,6 +80,15 @@ public class Client {
 }
 ```
 
+```text
+0
+1
+...
+9
+```
+
+Client 只用到 hasNext() 和 next()，ConcreteAggregate 把数组换成链表时，只要同时换掉迭代器，Client 不用改。
+
 ### JDK 中的应用
 - [java.util.Iterator](http://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html)
 - [java.util.Enumeration](http://docs.oracle.com/javase/8/docs/api/java/util/Enumeration.html)
@@ -87,4 +96,4 @@ public class Client {
 ## 参考资料
 
 - 弗里曼. Head First 设计模式 [M]. 中国电力出版社, 2007.
-- Gamma E. 设计模式: 可复用面向对象软件的基础 [M]. 机械工业出版社, 2007.
+- Gamma E. 设计模式：可复用面向对象软件的基础 [M]. 机械工业出版社, 2007.