求解决越界的问题，各位大神帮个忙！

Question

import java.io.*;
import java.util.*;
public class hou
{
public static void main(String[] args)
{
final int MAX=100;
InputStream input=System.in;
InputStreamReader reader=new InputStreamReader(input);
BufferedReader buf=new BufferedReader(reader); char str[]=new char[MAX];
char exp[]=new char[MAX];
char stack[]=new char[MAX];
String temp=null,line;
char ch;
int flag=1;
int i=0,j=0,t=0,top=0;
while(true)
{     System.out.println();
    System.out.println("============将中缀表达式转换为后缀表达式=============");
    System.out.print("中缀表达式:");
    try{
    temp=buf.readLine();
    }catch(Exception e){
     e.printStackTrace();
    }     if(temp.equals("exit"))
    {
       System.out.println("退出!");
        break;
    }
    break;
     }
line=temp.replaceAll(" ","");                     //去除空格        if(input!=null){                                 //没有输入
        try{
           input.close();
            }catch(Exception e){
              e.printStackTrace();
             }        str=line.toCharArray();
                for(int m=line.length()-1;m>=0;m--)
        {
         ch=str[i];
         if((ch>='a'&&ch<='z')||(ch>='0'&&ch<='9'))//字符为数字或者字母
         {
                   exp[t]=ch;
                   t++;
                }            else if(ch=='(')                        //若为左括号则压栈
             {
                   top++;
                   stack[top]=ch;
                }
            else if(ch==')')                     //为右括号时
             {
                  while(stack[top]!='(')
                  {
                  exp[t]=stack[top];
                  top--;
                  t++;
                  }
                  top--;
                }
            else if(ch=='+'||ch=='-')
             {
                  while(top!=0&&stack[top]!='(')
                 {
                     exp[t]=stack[top];
                     top--;
                     t++;
                     }
                  top++;
                  stack[top]=ch;
               }
           else if(ch=='*'||ch=='/')
            {
           while(stack[top]=='*'||stack[top]=='/')
            {
            exp[t]=stack[top];
            top--;
            t++;
           }
           top++;
           stack[top]=ch;
           }
           else {
           System.out.println("第 "+(i+1)+" 个字母开始出错!");
           flag=0;
           break;
              }
            i++;            ch=str[i];
            }
         if(flag!=0){
         while(top!=0){
         exp[t]=stack[top];
         t++;
         top--;
         }
         System.out.print("逆波兰式输出:");
         for(j=0;j<t;j++)
         System.out.print(exp[j]);
         System.out.println();     }
   }
        }     }程序编译可以通过，但是运行时，如输入2+3之类就提示错误，越界了
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 3
at hou.main(hou.java:111)

Answer 1

import java.io.*;
import java.util.*;
public class hou
{
public static void main(String[] args)
{
final int MAX=100;
InputStream input=System.in;
InputStreamReader reader=new InputStreamReader(input);
BufferedReader buf=new BufferedReader(reader); char str[]=new char[MAX];
char exp[]=new char[MAX];
char stack[]=new char[MAX];
String temp=null,line;
char ch;
int flag=1;
int i=0,j=0,t=0,top=0;
while(true)
{
System.out.println();
System.out.println("============将中缀表达式转换为后缀表达式=============");
System.out.print("中缀表达式:");
try{
temp=buf.readLine();
}catch(Exception e){
e.printStackTrace();
} if(temp.equals("exit"))
{
System.out.println("退出!");
break;
}
break;
}
line=temp.replaceAll(" ",""); //去除空格   if(input!=null){ //没有输入
  try{
input.close();
  }catch(Exception e){
e.printStackTrace();
  }   str=line.toCharArray();
  for(int m=line.length()-1;m>=0;m--)
  {
  ch=str[i];
  if((ch>='a'&&ch<='z')||(ch>='0'&&ch<='9'))//字符为数字或者字母
{
  exp[t]=ch;
  t++;
}else if(ch=='(') //若为左括号则压栈
{
  top++;
  stack[top]=ch;
} else if(ch==')') //为右括号时
{
  while(stack[top]!='(')
  {
  exp[t]=stack[top];
  top--;
  t++;
  }
  top--;
} else if(ch=='+'||ch=='-') 
{
  while(top!=0&&stack[top]!='(')
  {
  exp[t]=stack[top];
  top--;
  t++;
  }
  top++;
  stack[top]=ch;
}
else if ((ch=='*') || (ch=='/') )
{
  while ( (stack[top] == '*') || (stack[top] == '/'))
  {
  exp[t]=stack[top];
  top--;
  t++;
  }
  top++;
  stack[top]=ch;
}else {
  System.out.println("第 "+(i+1)+" 个字母开始出错!");
  flag=0;
  break;
}
i++; ch=str[i];
}
  if(flag!=0){
  while ((top!=0 ) && (t < exp.length) ){
exp[t]=stack[top];
t++;
top--;
  }
  System.out.print("逆波兰式输出:");
  for(j=0;j<t;j++)
System.out.print(exp[j]);
  System.out.println();   }
}
  }  }

Answer 2

          if(flag!=0){
     
         while ((top!=0 ) && (t < exp.length) ){                exp[t]=stack[top];
                t++;
                top--;
              }
              System.out.print("逆波兰式输出:");
              for(j=0;j<t;j++)
                System.out.print(exp[j]);
              System.out.println();          }
        }
      }  }