// ListNode.java: node for a linked list
public class ListNode {
   public int data;
   public ListNode next;

   public ListNode(int newdata) {
      // would be this way by default
      data = newdata;
      next = null;
   }
}
// LinkdedList.java: basic linked list
public class LinkedList {

   private ListNode first; // front, top
   private ListNode last;  // rear

   public LinkedList() {
      last = null;
      first = null;
   }

   public void addLast(int dataItem) {
      // or add to rear, i.e. enqueue
      if (last == null) { // empty linked list
         last = new ListNode(dataItem);
         first = last;
      }
      else { // case of non-empty linked list
         last.next = new ListNode(dataItem);
         last = last.next;
      }
   }

   public void addFirst(int dataItem) {
      // or add to front, i.e. dequeue, or push
      ListNode newNode = new ListNode(dataItem);
      newNode.next = first;
      first = newNode;
      if (last == null) // adding to empty list
         last = newNode;   
   }

   public int removeFirst() {
      // or pop
      int valueToReturn = first.data;
      first = first.next;
      if (first == null) last = null;
      return valueToReturn;
   }

   public boolean empty() {
      return first == null;
   }

   public void printList() {
   // first to last, or front to rear
      ListNode temp = first;
      while (temp != null) {
         System.out.print(temp.data  + " ");
         temp = temp.next;
      }
      System.out.println();
   }

   public void printReverse() {
      printReverse0(first);
      System.out.println();
   }
   public void printReverse0(ListNode temp) {
   // last to first, or rear to front
      if (temp != null) {
         printReverse0(temp.next);
         System.out.print(temp.data  + " ");
      }
   }
}

// Stack.java: inherited from linked list
public class Stack extends LinkedList{

   public void push(int dataItem) {
      addFirst(dataItem);
   }

   public int pop() {
      return removeFirst();
   }
}
// Queue.java: inherited from linked list
public class Queue extends LinkedList{

   public void enqueue(int dataItem) {
      addLast(dataItem);
   }

   public int dequeue() {
      return removeFirst();
   }
}
// ListTest.java: test stack and queue
public class ListTest{

   public static void main(String[] args) {
      int[] a = {2, 3, 5, 7, 11, 13};

      Queue q = new Queue();
      for (int i = 0; i < a.length; i++)
         q.enqueue(a[i]);
      System.out.println("Queue:");
      q.printList();
      q.printReverse();
      int t = q.dequeue();
      System.out.print(t + " ");
      t = q.dequeue();
      System.out.print(t + "\n");

      Stack s = new Stack();
      for (int i = 0; i < a.length; i++)
         s.push(a[i]);
      System.out.println("Stack:");
      s.printList();
      s.printReverse();
      t = s.pop();
      System.out.print(t + " ");
      t = s.pop();
      System.out.print(t + "\n");
   }
}

Queue:
2 3 5 7 11 13 
13 11 7 5 3 2 
2 3
Stack:
13 11 7 5 3 2 
2 3 5 7 11 13
13 11