/**

 * java数据结构之栈的实现

 * 2016/4/26

 **/

package cn.Link;

public class Stack{

    Node tail = new Node();

    Node nowNode = new Node();   //永远指向栈顶

    int size;

    Stack(){};

    Stack(String date){

        this.tail.date = date;

        this.tail.next = null;

        this.nowNode.next = this.tail;

        this.size = 1;

    }

    //节点类

    class Node{

        String date;

        Node next;

        Node(){};

        Node(String date){

            this.date = date;

        }

    }

    //向栈中插入数据

    public void Push(String date){

        Node preNode = new Node(date);

        preNode.next = this.nowNode.next;

       this.nowNode.next = preNode;

       this.size++;

       System.out.println("数据"+date+"被入栈");

    }

    //出栈操作

    public void Pop(){

        if(this.nowNode.next != this.tail){

          System.out.println("数据"+this.nowNode.next.date+"被移除栈");

          this.nowNode.next = this.nowNode.next.next;

        }else{

            nowNode.next = null;

            System.out.println("此栈没有数据，数据为空");

        }

        this.size--;

    }

    //遍历栈输出

    public void PrintStack(){

        Node preNode = new Node();

        preNode.next = this.nowNode.next;

        System.out.print("遍历输出栈： ");

        while(preNode.next != null){

            System.out.print(" -->"+preNode.next.date);

            preNode.next = preNode.next.next;

        }

        System.out.println("+++++++++++当前栈的长度为"+this.size);

    }

    //清空栈

    public void clear(){

        this.nowNode.next = null;

        this.tail = null;

        this.size = 0;

        System.out.println("栈已被清空");

    }

    public static void main(String[] args){

       Stack stack = new Stack("sum1");

        stack.Push("sum2");

        stack.Push("sum3");

        stack.Push("sum4");

        stack.Push("sum5");

        stack.Push("sum6");

        stack.Pop();

        stack.Push("sum7");

        stack.Push("sum8");

        stack.PrintStack();

        stack.clear();

    }

}