java实现——007用两个栈实现队列

 1 import java.util.Stack;

 2

 3 public class T007 {

 4     public static void main(String[] args) {

 5         Queue q = new Queue();

 6         q.stack1 = new Stack();

 7         q.stack2 = new Stack();

 8         q.appendTail(1);

 9         System.out.println(q.stack1.toString());

10         System.out.println(q.stack2.toString());

11         q.appendTail(2);

12         q.appendTail(3);

13         q.deleteHead();

14         System.out.println(q.stack1.toString());

15         System.out.println(q.stack2.toString());

16     }

17

18     public static class Queue {

19         private Stack<Integer> stack1;

20         private Stack<Integer> stack2;

21

22         public void appendTail(int e) {

23             stack1.push(e);

24         }

25

26         public void deleteHead() {

27             if (stack2.size() <= 0) {

28                 while (stack1.size() > 0) {

29                     int data = stack1.peek();

30                     stack1.pop();

31                     stack2.push(data);

32                 }

33             }

34             if (stack2.size() == 0)

35                 System.out.println("queue is empty");

36             int head = stack2.peek();

37             stack2.pop();

38         }

39     }

40 }

java实现——007用两个栈实现队列