栈_对表达式求值

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();
}
}