Stack을 이용한 Queue의 구현

public class QueueUsingStack{
 
    // define 2 stacks for implementing queue
    private Stack stack1 = new Stack();
    private Stack stack2 = new Stack();
 
    // Enque - push the element in stack1
    public void enque(int element)
        stack1.push(element);
 
    // Dequeue - pop the element from stack2 
    // and pop the element from stack1
    public E deque(){
        if(stack2.isEmpty())
        {
            while(!stack1.isEmpty())
                stack2.push(stack1.pop());
        }
 
        return stack2.pop();
    }
 
}