Iterator pattern

src/main/java/iterator/ArrayList_.java

@@ -0,0 +1,45 @@
+package iterator;
+
+public class ArrayList_ implements Collection_{
+    Object[] objects = new Object[10];
+    private int size = 0;
+
+    @Override
+    public void add(Object o) {
+        if(size == objects.length){
+            Object[] newObjects = new Object[objects.length*2];
+            System.arraycopy(objects,0, newObjects, 0, objects.length);
+            objects = newObjects;
+        }
+        objects[size] = o;
+        size++;
+    }
+
+    @Override
+    public int size() {
+        return size;
+    }
+
+    @Override
+    public Iterator_ iterator() {
+        return new ArrayListIterator();
+    }
+
+    private class ArrayListIterator implements Iterator_{
+        private int currentSize = 0;
+        @Override
+        public boolean hasNext() {
+            if(currentSize >= size){
+                return false;
+            }
+            return true;
+        }
+
+        @Override
+        public Object next() {
+            Object o = objects[currentSize];
+            currentSize ++;
+            return o;
+        }
+    }
+}

src/main/java/iterator/Collection_.java

@@ -0,0 +1,7 @@
+package iterator;
+
+public interface Collection_ {
+    void add(Object o);
+    int size();
+    Iterator_ iterator();
+}

src/main/java/iterator/Iterator_.java

@@ -0,0 +1,6 @@
+package iterator;
+
+public interface Iterator_ {
+    boolean hasNext();
+    Object next();
+}

src/main/java/iterator/LinkedList_.java

@@ -0,0 +1,40 @@
+package iterator;
+
+public class LinkedList_ implements Collection_{
+    Node head;
+    Node tail;
+    int size = 0;
+
+    @Override
+    public void add(Object o) {
+        Node n = new Node(o);
+        n.next = null;
+        if(head == null){
+            head = n;
+        }else{
+            tail.next = n;
+        }
+        tail = n;
+        size ++;
+    }
+
+    @Override
+    public int size() {
+        return size;
+    }
+
+    @Override
+    public Iterator_ iterator() {
+        return null;
+    }
+
+
+    private class Node{
+        Object o;
+        Node next;
+
+        public Node(Object o) {
+            this.o = o;
+        }
+    }
+}

src/main/java/iterator/Main.java

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+package iterator;
+
+import java.util.LinkedList;
+
+public class Main {
+    public static void main(String[] args) {
+        Collection_ a = new ArrayList_();
+        for (int i = 0; i < 15; i++) {
+            a.add("testA " + i);
+        }
+        System.out.println(a.size());
+
+        Collection_ l = new LinkedList_();
+        for (int i = 0; i < 15; i++) {
+            l.add("testL " + i);
+        }
+        System.out.println(l.size());
+
+        Iterator_ it = a.iterator();
+        while (it.hasNext()){
+            Object o = it.next();
+            System.out.println(o);
+        }
+    }
+}