diff --git a/src/main/java/com/msb/iterator/v4/Dog.java b/src/main/java/com/msb/iterator/v4/Dog.java
new file mode 100644
index 0000000..0efd176
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v4/Dog.java
@@ -0,0 +1,27 @@
+package com.msb.iterator.v4;/**
+ * @Author bingor
+ * @Date 2022/10/17 18:59
+ * @Description: com.msb.iterator.v4
+ * @Version: 1.0
+ */
+
+/**
+ *@ClassName Dog
+ *@Description TODO
+ *@Author bingor
+ *@Date 2022/10/17 18:59
+ *@Version 3.0
+ */
+public class Dog {
+    private int id;
+    public Dog(int id) {
+        this.id = id;
+    }
+
+    @Override
+    public String toString() {
+        return "Dog{" +
+                "id=" + id +
+                '}';
+    }
+}
diff --git a/src/main/java/com/msb/iterator/v4/Main.java b/src/main/java/com/msb/iterator/v4/Main.java
index fe93066..9db4aa0 100644
--- a/src/main/java/com/msb/iterator/v4/Main.java
+++ b/src/main/java/com/msb/iterator/v4/Main.java
@@ -16,7 +16,7 @@ public class Main {
     public static void main(String[] args) {
         Collection_ list = new LinkedList_();
         for (int i=0; i<15; i++) {
-            list.add(i);
+            list.add(new Dog(i));
         }
 
         Iterator_ iterator = list.iterator();
diff --git a/src/main/java/com/msb/iterator/v5/ArrayList_.java b/src/main/java/com/msb/iterator/v5/ArrayList_.java
new file mode 100644
index 0000000..e533baf
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v5/ArrayList_.java
@@ -0,0 +1,62 @@
+package com.msb.iterator.v5;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:06
+ * @Description: com.msb.iterator.v1
+ * @Version: 1.0
+ */
+
+import java.util.Collection;
+
+/**
+ *@ClassName ArrayList_
+ *@Description TODO
+ *@Author bingor
+ *@Date 2022/10/17 17:06
+ *@Version 3.0
+ */
+public class ArrayList_<T> implements Collection_<T> {
+
+    private T[] objects = (T[]) new Object[10];
+    private int index = 0;
+    private int step = 0;
+
+    @Override
+    public void add(T o) {
+        if(index == objects.length) {
+            T[] newObjects = (T[]) new Object[2*objects.length];
+            System.arraycopy(objects, 0, newObjects, 0, objects.length);
+            objects = newObjects;
+        }
+        objects[index] = o;
+        index ++;
+    }
+
+    @Override
+    public int size() {
+        return index;
+    }
+
+    @Override
+    public Iterator_ iterator() {
+        return new ArrayListIterator();
+    }
+
+    private class ArrayListIterator implements Iterator_<T> {
+        private int currentIndex = 0;
+
+        @Override
+        public boolean hashNext() {
+            if(this.currentIndex >= objects.length) return false;
+            if(objects[this.currentIndex] == null) return false;
+            return true;
+        }
+
+        @Override
+        public T next() {
+            return objects[this.currentIndex++];
+        }
+
+    }
+
+
+}
diff --git a/src/main/java/com/msb/iterator/v5/Collection_.java b/src/main/java/com/msb/iterator/v5/Collection_.java
new file mode 100644
index 0000000..3d18081
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v5/Collection_.java
@@ -0,0 +1,13 @@
+package com.msb.iterator.v5;
+
+/**
+ * @Author bingor
+ * @Date 2022/10/17 17:53
+ * @Description: com.msb.iterator.v3
+ * @Version: 1.0
+ */
+public interface Collection_<T> {
+    public void add(T o);
+    public int size();
+    public Iterator_<T> iterator();
+}
diff --git a/src/main/java/com/msb/iterator/v5/Iterator_.java b/src/main/java/com/msb/iterator/v5/Iterator_.java
new file mode 100644
index 0000000..b904662
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v5/Iterator_.java
@@ -0,0 +1,12 @@
+package com.msb.iterator.v5;
+
+/**
+ * @Author bingor
+ * @Date 2022/10/17 18:00
+ * @Description: com.msb.iterator.v4
+ * @Version: 1.0
+ */
+public interface Iterator_<T> {
+    public boolean hashNext();
+    public T next();
+}
diff --git a/src/main/java/com/msb/iterator/v5/LinkedList_.java b/src/main/java/com/msb/iterator/v5/LinkedList_.java
new file mode 100644
index 0000000..749abb9
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v5/LinkedList_.java
@@ -0,0 +1,74 @@
+package com.msb.iterator.v5;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:14
+ * @Description: com.msb.iterator.v2
+ * @Version: 1.0
+ */
+
+/**
+ *@ClassName LinkedList
+ *@Description 相比数组，这个容器不用考虑边界问题，可以动态扩展
+ *@Author bingor
+ *@Date 2022/10/17 17:14
+ *@Version 3.0
+ */
+public class LinkedList_<T> implements Collection_<T> {
+
+    private int size = 0;
+    private Node head = null;
+    private Node tail = null;
+
+    @Override
+    public void add(T o) {
+        Node<T> node = new Node(o);
+        node.next = null;
+
+        if(head == null) {
+            head = node;
+            tail = node;
+        }
+
+        tail.next = node;
+        tail = node;
+        size++;
+    }
+
+    @Override
+    public int size() {
+        return size;
+    }
+
+    @Override
+    public Iterator_<T> iterator() {
+        return new LinkedListIterator();
+    }
+
+    private class LinkedListIterator implements Iterator_<T> {
+
+        private Node currentNode = head;
+
+        @Override
+        public boolean hashNext() {
+            if(null == currentNode) return false;
+            return true;
+        }
+
+        @Override
+        public T next() {
+            T o = (T) currentNode.o;
+            currentNode = currentNode.next;
+            return o;
+        }
+    }
+
+    private class Node<T> {
+        private T o;
+        private Node next;
+
+        public Node(T o) {
+            this.o = o;
+        }
+    }
+
+}
+
diff --git a/src/main/java/com/msb/iterator/v5/Main.java b/src/main/java/com/msb/iterator/v5/Main.java
new file mode 100644
index 0000000..67122d4
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v5/Main.java
@@ -0,0 +1,29 @@
+package com.msb.iterator.v5;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:54
+ * @Description: com.msb.iterator.v3
+ * @Version: 1.0
+ */
+
+import com.msb.iterator.v4.Dog;
+
+/**
+ *@ClassName Main
+ *@Description TODO
+ *@Author bingor
+ *@Date 2022/10/17 17:54
+ *@Version 3.0
+ */
+public class Main {
+    public static void main(String[] args) {
+        Collection_ list = new LinkedList_();
+        for (int i=0; i<15; i++) {
+            list.add(new Dog(i));
+        }
+
+        Iterator_ iterator = list.iterator();
+        while (iterator.hashNext()) {
+            System.out.println(iterator.next());
+        }
+    }
+}