数组实现栈

栈也是数据结构中的一种,是一种先进后出结构,代码如下

package com.zgz.search;
public class MyStack {
   private int[] arr;
   public MyStack(){
       arr = new int[0];
   }
    /**
     * 压入元素
     */
   public void push(int value){
       int[] newArr = new int[arr.length+1];
       for(int i=0;i<arr.length;i++){
           newArr[i] = arr[i];
       }
       newArr[newArr.length-1] = value;
       this.arr = newArr;
   }
    /**
     * 取出栈顶元素
     * @return
     */
   public int pop(){
       if(arr.length==0){
           return -1;
       }
       int value = arr[arr.length-1];
       int[] newArr = new int[arr.length-1];
       for(int i=0;i<arr.length-1;i++){
           newArr[i] = arr[i];
       }
       arr = newArr;
       return value;
   }
    /**
     * 查看栈顶元素
    @return
     */
   public int peek(){
        return arr.length>0?arr[arr.length-1]:-1;
   }
   public boolean isEmpty(){
       return arr.length==0;
    }
}