Stack_CreateQueue.java

import java.util.Stack;

public class Queue_TwoStack {

    private static Stack<Object> stack1 = new Stack<>();
    private static Stack<Object> stack2 = new Stack<>();

    public static void enqueue(Object item) {
        stack1.push(item);
    }

    public static Object dequeue() {
        while (!stack1.empty())
            stack2.push(stack1.pop());
        if (!stack2.empty())
            return stack2.pop();
        else
            return null;
    }

    public static Object getFront() {
        while (!stack1.empty())
            stack2.push(stack1.pop());
        if (!stack2.empty())
            return stack2.peek();
        else
            return null;
    }

    public static void main(String[] args) {
        int[] a = {1, 2, 3};
        for (int i = 0; i < a.length; i++) {
            enqueue(a[i]);
            System.out.println(a[i]+" ");
        }
        System.out.println("dequeue:" + dequeue());
        System.out.println("getFront:" + getFront());
    }
}