不移除元素遍历栈和队列

一、Queue的遍历

 

import java.util.Queue; 
import java.util.concurrent.LinkedBlockingQueue; 

/** 
* 队列的遍历 
* 
* @author leizhimin 2009-7-22 15:05:14 
*/ 
public class TestQueue { 
        public static void main(String[] args) { 
                Queue<Integer> q = new LinkedBlockingQueue<Integer>(); 
                //初始化队列 
                for (int i = 0; i < 5; i++) { 
                        q.offer(i); 
                } 
                System.out.println("-------1-----"); 
                //集合方式遍历，元素不会被移除 
                for (Integer x : q) { 
                        System.out.println(x); 
                } 
                System.out.println("-------2-----"); 
                //队列方式遍历，元素逐个被移除 
                while (q.peek() != null) { 
                        System.out.println(q.poll()); 
                } 
        } 
}

 

-------1----- 
0 
1 
2 
3 
4 
-------2----- 
0 
1 
2 
3 
4 

Process finished with exit code 0

 

二、Stack的遍历

 

import java.util.Stack; 

/** 
* 栈的遍历 
* 
* @author leizhimin 2009-7-22 14:55:20 
*/ 
public class TestStack { 
        public static void main(String[] args) { 
                Stack<Integer> s = new Stack<Integer>(); 
                for (int i = 0; i < 10; i++) { 
                        s.push(i); 
                } 
                //集合遍历方式 
                for (Integer x : s) { 
                        System.out.println(x); 
                } 
                System.out.println("------1-----"); 
                //栈弹出遍历方式 
//                while (s.peek()!=null) {     //不健壮的判断方式，容易抛异常，正确写法是下面的 
                while (!s.empty()) { 
                        System.out.println(s.pop()); 
                } 
                System.out.println("------2-----"); 
                //错误的遍历方式 
//                for (Integer x : s) { 
//                        System.out.println(s.pop()); 
//                } 
        } 
}

 

0 
1 
2 
3 
4 
------1----- 
4 
3 
2 
1 
0 
------2----- 

Process finished with exit code 0