栈_对表达式求值

题目：“+”表示将后面的字母压入栈，“-”表示弹出栈顶字母并打印它。

import java.util.Scanner;import java.util.Stack;public class A {    //+U+n+c-+e+r+t---+a-+i-+n+t+y--+z-+r+u---+l+e+s--    public static void main(String[] args) {        System.out.print("请输入：");        Scanner in = new Scanner(System.in);        String inputString = in.nextLine();        char[] aa = inputString.toCharArray();        Stack<Character> stack1 = new Stack<Character>();        int len = aa.length;        for(int i = 0;i<len;i++){            if(aa[i]=='+')                stack1.push(aa[i+1]);            else if(aa[i]=='-')                System.out.print(stack1.pop());            else{}        }        in.close();     }}