//输入整数将整数反相打印.比如输入8000.输出0008

import *;
public class xt3
{
    static BufferedReader keyboard=new BufferedReader(new InputStreamReader(System.in));
    public static void main(String[] args)throws IOException
    {
        int num;
        int longth;
        String leng;
        System.out.print("请输入一个整数:");
        leng=keyboard.readLine();
        longth=leng.length();
        for(num=longth;num>=0;num--)
          {            
              System.out.print(leng.substring((longth-2),longth));         
              longth--;
          }
    }
}
编译出错

不是空格的问题
编译可以通过!
运行时出错
010000Exception in thread "main" java.lang.StringIndexOutOfBoundsException: Stri
ng index out of range: -1
        at java.lang.String.substring(String.java:1438)
        at xt3.main(xt3.java:15)

问题解决并不像楼上说的问题 import java.io.*; import java.lang.*; public class xt3 { static BufferedReader keyboard=new BufferedReader(new InputStreamReader(System.in)); public static void main(String[] args)throws IOException { int num; int longth; String leng; System.out.print("请输入一个整数:"); leng=keyboard.readLine(); longth=leng.length(); for(;longth>0;longth--)

{ System.out.print(leng.substring((longth-1),longth)); } } }