[Java算法分析与设计]--顺序栈的实现

　　在程序的世界，栈的应用是相当广泛的。其后进先出的特性，我们可以应用到诸如计算、遍历、代码格式校对等各个方面。但是你知道栈的底层是怎么实现的吗？现在跟随本篇文章我们来一睹它的庐山真面目吧。

　　首先我们先定义Stack的接口如下：

 package com.chen.arithmetic_test.stack_test;

 /**
  * Created by ChenMP on 2017/7/4.
  */
 public interface Stack {
     //入栈
     public void push(Object obj) throws Exception;
     //出栈
     public Object pop() throws Exception;
     //获得栈顶元素
     public Object getTop() throws Exception;
     //判断栈是否为空
     public boolean isEmpty();
 }

　　接下来，我们看看它的实现类：

 package com.chen.arithmetic_test.stack_test;

 /**
  * Created by ChenMP on 2017/7/4.
  */
 public class SequenceStack implements Stack {
     private Object[] stack; //底层数据结构设计为对象数组
     private int top; //栈顶位置标记
     private int maxSize; //最大长度

     public SequenceStack() {
         this.stack = new Object[10];// 默认栈的长度为10
         this.top = 0;
         this.maxSize = 10;
     }

     public SequenceStack(int maxSize) {
         this.stack = new Object[maxSize];// 默认栈的长度为10
         this.top = 0;
         this.maxSize = maxSize;
     }

     @Override
     public void push(Object obj) throws Exception {
         if(top == maxSize)
             throw new Exception("堆栈已满！");

         stack[top] = obj; //添加入栈顶位置
         top++;  //栈顶位置标记+1
     }

     @Override
     public Object pop() throws Exception {
         if (0 == top)
             throw new Exception("堆栈为空！");

         Object returnObj = stack[top]; //获取栈顶位置数据对象
         stack[top] = null; //将该位置置为null，避免内存泄漏
         top--; //栈顶位置标记-1
         return returnObj ;
     }

     @Override
     public Object getTop() throws Exception {
         if (0 == top)
             throw new Exception("堆栈为空！");

         return stack[top-1];
     }

     @Override
     public boolean isEmpty() {
         return top>0?false:true;
     }
 }

　　来测试我们实现的顺序栈吧！

 package com.chen.arithmetic_test.stack_test;

 import java.util.Scanner;

 /**
  * Created by ChenMP on 2017/7/4.
  */
 public class TestStack {
     public static void main(String[] args) throws Exception {
         // TODO Auto-generated method stub
         SequenceStack stack = new SequenceStack(10);

         Scanner in = new Scanner(System.in);
         int temp;
         for(int i=0;i<10;i++)
         {
             System.out.println("请输入第"+(i+1)+"个整数：");
             temp = in.nextInt();
             stack.push(temp);
         }

         while(!stack.isEmpty())
         {
             System.out.println(stack.pop());
         }
     }
 }

　　通过上面的代码，其实也可以很清晰的理解顺序栈的实现原理对不对？给自己点个赞~