diff --git a/src/main/java/com/msb/iterator/v1/ArrayList_.java b/src/main/java/com/msb/iterator/v1/ArrayList_.java
new file mode 100644
index 0000000..eaecef4
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v1/ArrayList_.java
@@ -0,0 +1,44 @@
+package com.msb.iterator.v1;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:06
+ * @Description: com.msb.iterator.v1
+ * @Version: 1.0
+ */
+
+/**
+ *@ClassName ArrayList_
+ *@Description TODO
+ *@Author bingor
+ *@Date 2022/10/17 17:06
+ *@Version 3.0
+ */
+public class ArrayList_ {
+
+    private Object[] objects = new Object[10];
+    private int index = 0;
+
+    public void add(Object o) {
+        if(index == objects.length) {
+            Object[] newObjects = new Object[2*objects.length];
+            System.arraycopy(objects, 0, newObjects, 0, objects.length);
+            objects = newObjects;
+        }
+        objects[index] = o;
+        index ++;
+    }
+
+    public int size() {
+        return index;
+    }
+
+}
+
+class Main {
+    public static void main(String[] args) {
+        ArrayList_ list = new ArrayList_();
+        for (int i=0; i<15; i++) {
+            list.add(i);
+        }
+        System.out.println(list.size());
+    }
+}
diff --git a/src/main/java/com/msb/iterator/v2/LinkedList_.java b/src/main/java/com/msb/iterator/v2/LinkedList_.java
new file mode 100644
index 0000000..dc9f0f3
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v2/LinkedList_.java
@@ -0,0 +1,60 @@
+package com.msb.iterator.v2;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:14
+ * @Description: com.msb.iterator.v2
+ * @Version: 1.0
+ */
+
+import java.util.Arrays;
+
+/**
+ *@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_ {
+
+    private int size = 0;
+    private Node head = null;
+    private Node tail = null;
+
+    public void add(Object o) {
+        Node node = new Node(o);
+        node.next = null;
+
+        if(head == null) {
+            head = node;
+            tail = node;
+        }
+
+        tail.next = node;
+        tail = node;
+        size++;
+    }
+
+    public int size() {
+        return size;
+    }
+
+    private class Node {
+        private Object o;
+        private Node next;
+
+        public Node(Object o) {
+            this.o = o;
+        }
+    }
+
+}
+
+class Main {
+    public static void main(String[] args) {
+        LinkedList_ list = new LinkedList_();
+        for (int i=0; i<15; i++) {
+            list.add(i);
+        }
+        System.out.println(list.size());
+    }
+}
diff --git a/src/main/java/com/msb/iterator/v3/ArrayList_.java b/src/main/java/com/msb/iterator/v3/ArrayList_.java
new file mode 100644
index 0000000..991b9ea
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v3/ArrayList_.java
@@ -0,0 +1,36 @@
+package com.msb.iterator.v3;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:06
+ * @Description: com.msb.iterator.v1
+ * @Version: 1.0
+ */
+
+/**
+ *@ClassName ArrayList_
+ *@Description TODO
+ *@Author bingor
+ *@Date 2022/10/17 17:06
+ *@Version 3.0
+ */
+public class ArrayList_ implements Collection_ {
+
+    private Object[] objects = new Object[10];
+    private int index = 0;
+
+    @Override
+    public void add(Object o) {
+        if(index == objects.length) {
+            Object[] newObjects = 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;
+    }
+
+}
diff --git a/src/main/java/com/msb/iterator/v3/Collection_.java b/src/main/java/com/msb/iterator/v3/Collection_.java
new file mode 100644
index 0000000..40fdb41
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v3/Collection_.java
@@ -0,0 +1,12 @@
+package com.msb.iterator.v3;
+
+/**
+ * @Author bingor
+ * @Date 2022/10/17 17:53
+ * @Description: com.msb.iterator.v3
+ * @Version: 1.0
+ */
+public interface Collection_ {
+    public void add(Object o);
+    public int size();
+}
diff --git a/src/main/java/com/msb/iterator/v3/LinkedList_.java b/src/main/java/com/msb/iterator/v3/LinkedList_.java
new file mode 100644
index 0000000..053f42e
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v3/LinkedList_.java
@@ -0,0 +1,51 @@
+package com.msb.iterator.v3;/**
+ * @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_ implements Collection_ {
+
+    private int size = 0;
+    private Node head = null;
+    private Node tail = null;
+
+    @Override
+    public void add(Object o) {
+        Node 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;
+    }
+
+    private class Node {
+        private Object o;
+        private Node next;
+
+        public Node(Object o) {
+            this.o = o;
+        }
+    }
+
+}
+
diff --git a/src/main/java/com/msb/iterator/v3/Main.java b/src/main/java/com/msb/iterator/v3/Main.java
new file mode 100644
index 0000000..3c24daf
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v3/Main.java
@@ -0,0 +1,23 @@
+package com.msb.iterator.v3;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:54
+ * @Description: com.msb.iterator.v3
+ * @Version: 1.0
+ */
+
+/**
+ *@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(i);
+        }
+        System.out.println(list.size());
+    }
+}
diff --git a/src/main/java/com/msb/iterator/v4/ArrayList_.java b/src/main/java/com/msb/iterator/v4/ArrayList_.java
new file mode 100644
index 0000000..9d60de5
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v4/ArrayList_.java
@@ -0,0 +1,60 @@
+package com.msb.iterator.v4;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:06
+ * @Description: com.msb.iterator.v1
+ * @Version: 1.0
+ */
+
+/**
+ *@ClassName ArrayList_
+ *@Description TODO
+ *@Author bingor
+ *@Date 2022/10/17 17:06
+ *@Version 3.0
+ */
+public class ArrayList_ implements Collection_ {
+
+    private Object[] objects = new Object[10];
+    private int index = 0;
+    private int step = 0;
+
+    @Override
+    public void add(Object o) {
+        if(index == objects.length) {
+            Object[] newObjects = 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_ {
+        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 Object next() {
+            return objects[this.currentIndex++];
+        }
+
+    }
+
+
+}
diff --git a/src/main/java/com/msb/iterator/v4/Collection_.java b/src/main/java/com/msb/iterator/v4/Collection_.java
new file mode 100644
index 0000000..b919d0f
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v4/Collection_.java
@@ -0,0 +1,13 @@
+package com.msb.iterator.v4;
+
+/**
+ * @Author bingor
+ * @Date 2022/10/17 17:53
+ * @Description: com.msb.iterator.v3
+ * @Version: 1.0
+ */
+public interface Collection_ {
+    public void add(Object o);
+    public int size();
+    public Iterator_ iterator();
+}
diff --git a/src/main/java/com/msb/iterator/v4/Iterator_.java b/src/main/java/com/msb/iterator/v4/Iterator_.java
new file mode 100644
index 0000000..56f74e7
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v4/Iterator_.java
@@ -0,0 +1,12 @@
+package com.msb.iterator.v4;
+
+/**
+ * @Author bingor
+ * @Date 2022/10/17 18:00
+ * @Description: com.msb.iterator.v4
+ * @Version: 1.0
+ */
+public interface Iterator_ {
+    public boolean hashNext();
+    public Object next();
+}
diff --git a/src/main/java/com/msb/iterator/v4/LinkedList_.java b/src/main/java/com/msb/iterator/v4/LinkedList_.java
new file mode 100644
index 0000000..1dbeda3
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v4/LinkedList_.java
@@ -0,0 +1,74 @@
+package com.msb.iterator.v4;/**
+ * @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_ implements Collection_ {
+
+    private int size = 0;
+    private Node head = null;
+    private Node tail = null;
+
+    @Override
+    public void add(Object o) {
+        Node 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_ iterator() {
+        return new LinkedListIterator();
+    }
+
+    private class LinkedListIterator implements Iterator_ {
+
+        private Node currentNode = head;
+
+        @Override
+        public boolean hashNext() {
+            if(null == currentNode) return false;
+            return true;
+        }
+
+        @Override
+        public Object next() {
+            Object o = currentNode.o;
+            currentNode = currentNode.next;
+            return o;
+        }
+    }
+
+    private class Node {
+        private Object o;
+        private Node next;
+
+        public Node(Object o) {
+            this.o = o;
+        }
+    }
+
+}
+
diff --git a/src/main/java/com/msb/iterator/v4/Main.java b/src/main/java/com/msb/iterator/v4/Main.java
new file mode 100644
index 0000000..fe93066
--- /dev/null
+++ b/src/main/java/com/msb/iterator/v4/Main.java
@@ -0,0 +1,27 @@
+package com.msb.iterator.v4;/**
+ * @Author bingor
+ * @Date 2022/10/17 17:54
+ * @Description: com.msb.iterator.v3
+ * @Version: 1.0
+ */
+
+/**
+ *@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(i);
+        }
+
+        Iterator_ iterator = list.iterator();
+        while (iterator.hashNext()) {
+            System.out.println(iterator.next());
+        }
+    }
+}