Adding Queue linked list client

clients/src/main/java/com/hithomelabs/clients/ArrayQueueClient.java

@@ -1,9 +1,7 @@
 package com.hithomelabs.clients;
 
 import com.hithomelabs.princeton1.module4.ArrayQueue;
-import com.hithomelabs.princeton1.module4.ArrayStack;
 import com.hithomelabs.princeton1.module4.Queue;
-import com.hithomelabs.princeton1.module4.Stack;
 
 public class ArrayQueueClient {
     public static void main(String[] args) {

clients/src/main/java/com/hithomelabs/clients/LinkedQueueClient.java

@@ -0,0 +1,20 @@
+package com.hithomelabs.clients;
+
+import com.hithomelabs.princeton1.module4.LinkedQueue;
+import com.hithomelabs.princeton1.module4.Queue;
+
+public class LinkedQueueClient {
+    public static void main(String[] args) {
+        Queue<Integer> queue = new LinkedQueue<Integer>();
+        for(int i = 0; i < 21; i++){
+            queue.enqueue(i);
+        }
+        for(int i = 0; i < 13; i++){
+            System.out.println(queue.dequeue());
+        }
+
+        // Using object s, as stack is generic but every java Object has implementation of toString()
+        for (Object s : queue)
+            System.out.println(s);
+        }
+    }

clients/src/main/java/com/hithomelabs/clients/LinkedStackClient.java

@@ -4,7 +4,7 @@ package com.hithomelabs.clients;
 import com.hithomelabs.princeton1.module4.LinkedStack;
 import com.hithomelabs.princeton1.module4.Stack;
 
-public class LinkedArrayClient {
+public class LinkedStackClient {
     public static void main(String[] args) {
         Stack<String> stack = new LinkedStack<String>();
         stack.push("hello");

module4/src/main/java/com/hithomelabs/princeton1/module4/LinkedQueue.java

@@ -0,0 +1,74 @@
+package com.hithomelabs.princeton1.module4;
+
+import javax.annotation.Nonnull;
+import java.util.Iterator;
+
+public class LinkedQueue<E> extends Queue<E>{
+
+    Node head;
+    Node tail;
+    int size;
+
+    private class Node{
+        E value;
+        Node next;
+
+        Node(E value){
+            this.value = value;
+        }
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return size==0;
+    }
+
+    @Override
+    public E dequeue() {
+        if(isEmpty())
+            return null;
+        E element = head.value;
+        // Only a single element is present
+        if (head == tail){
+            tail = null;
+        }
+        head = head.next;
+        --size;
+        return element;
+    }
+
+    @Override
+    public void enqueue(E element) {
+        Node newNode = new Node(element);
+        if(isEmpty())
+            head = newNode;
+        else
+            tail.next = newNode;
+        tail = newNode;
+        ++size;
+    }
+
+    @Override
+    public int size() {
+        return size;
+    }
+
+    @Override
+    @Nonnull
+    public Iterator<E> iterator() {
+        return new Iterator<E>() {
+            Node current = head;
+            @Override
+            public boolean hasNext() {
+                return current != tail;
+            }
+
+            @Override
+            public E next() {
+                E element = current.value;
+                current = current.next;
+                return element;
+            }
+        };
+    }
+}