Queue using stack

Problem

Implement a queue using stack.

Solution

We can implement a queue using two stacks. while enqueueing we will put into stack one. while dequeuing we will pop from stack two. when stack two is empty we will pop the stack one and put all items into stack two.

Code

import java.util.Stack;


public class QueueUsingStack
{
 private Stack<Integer>stackPop=new Stack<Integer>();
 private Stack<Integer>stackPush=new Stack<Integer>();
 
 public void enqueue(int a)
 {
  stackPush.push(a);
 }
 public int dequeue()
 {
  if(stackPop.isEmpty())
   while(!stackPush.isEmpty())
    stackPop.push(stackPush.pop());
  return stackPop.pop();
 }
}