运行错误是：      
please input the inorder expression
1+2
the postorder expression is
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String
index out of range: -1
        at java.lang.String.charAt(String.java:507)
        at stack1.main(stack1.java:18)
源码如下：
import java.io.*;
public class stack1{
         public static void main(String args[]){ 
          stackarray operator=new stackarray();
          String inorder=new String();
          int inposition=0;
          int operator1=0;
          System.out.println("please input the inorder expression");
          BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
          try{
          inorder=input.readLine();}
          catch(IOException e){
          System.out.println(e);}
          System.out.println("the postorder expression is");
         
          for(inposition=-1;;inposition++){
          while (true){
          if(operator.isoperator(inorder.charAt(inposition))){
          if((operator.top==-1)||(char)inorder.charAt(inposition)=='(')
                     operator.push(inorder.charAt(inposition));
                  else
          {   if((char)inorder.charAt(inposition)==')')
                {if(operator.astack[operator.top]!=40)
                   {operator1=operator.pop();
                       System.out.print((char)operator1);
          }
          }
          else
          {if(operator.priority(inorder.charAt(inposition))
          =inorder.length())
                break;
                
            }
           while(operator.top!=-1)
            {
             operator1=operator.pop();
             System.out.print((char)operator1);
            }
        }
        }
    }
        class stackarray{
         int maxsize=20;
         int[] astack=new int[maxsize];
         int top=-1;
         public void push(int value){
         int i;
         if(top>=maxsize)
         System.out.println("the stack is full");
         else{
         top++;
         astack[top]=value;
         }
         }
         public int pop(){
         int temp;
         int i;
         if(top

    

 

新手初到跪求大虾linux系统自动生成同名的文件与后缀~文件解决办法