java实现——007用两个栈实现队列

 import java.util.Stack;

 public class T007 {
     public static void main(String[] args) {
         Queue q = new Queue();
         q.stack1 = new Stack();
         q.stack2 = new Stack();
         q.appendTail(1);
         System.out.println(q.stack1.toString());
         System.out.println(q.stack2.toString());
         q.appendTail(2);
         q.appendTail(3);
         q.deleteHead();
         System.out.println(q.stack1.toString());
         System.out.println(q.stack2.toString());
     }

     public static class Queue {
         private Stack<Integer> stack1;
         private Stack<Integer> stack2;

         public void appendTail(int e) {
             stack1.push(e);
         }

         public void deleteHead() {
             if (stack2.size() <= 0) {
                 while (stack1.size() > 0) {
                     int data = stack1.peek();
                     stack1.pop();
                     stack2.push(data);
                 }
             }
             if (stack2.size() == 0)
                 System.out.println("queue is empty");
             int head = stack2.peek();
             stack2.pop();
         }
     }
 }