Stack Using Two Queues

StackUsingQueue.java

import java.util.LinkedList;
import java.util.Queue;

/**
 * Author : Deepak Singhvi
 */
public class StackUsingQueue {

  private Queue<Integer> q1 = new LinkedList<>();
  private Queue<Integer> q2 = new LinkedList<>();

  public static void main(String args[]){
    StackUsingQueue s = new StackUsingQueue();
    s.push(1);
    s.push(2);
    s.push(3);

    System.out.println("1 :" + s.pop());
    System.out.println("2 :" + s.pop());
    System.out.println("3 :" + s.pop());
    System.out.println("4 :" + s.pop());
  }

  public void push(Integer element){
    q2.add(element);
    while(!q1.isEmpty()) {
      q2.add(q1.poll());
    }
    Queue<Integer> temp = q1;
    q1 = q2;
    q2 = temp;
  }

  public Integer pop() {
    if(q1.isEmpty()) {
      System.out.println("Queue Empty");
      return null;
    }
    return q1.poll();
  }
}