import java.util.ArrayList;
import java.util.*;
public class Solution {
    public boolean IsPopOrder(int [] pushA,int [] popA) {
        int len = pushA.length;
        int j=0;
        Stack stack = new Stack<Integer>();
        for(int i=0;i<len;i++){
            stack.push(pushA[i]);
            while(!stack.empty()&&(int)(stack.peek())==popA[j]&&j<len){
                stack.pop();
                j++;
            }     
        }
        return stack.isEmpty();
    }
}

注意点: 1.stack.peek()转换为int类型再比较大小,这里无法使用intValue()