题目：给一个不多于5位的正整数，要求：一、求它是几位数，二、逆序打印出各位数字。

程序设计：

import java.util.Scanner;public class Ex24 {public static void main(String[] args) { Ex24 tn = new Ex24(); Scanner s = new Scanner(System.in); long a = s.nextLong(); if(a < 0 || a > 100000) { System.out.println("Error Input, please run this program Again"); System.exit(0); } if(a >=0 && a <=9) { System.out.println( a + "是一位数"); System.out.println("按逆序输出是" + '\n' + a); } else if(a >= 10 && a <= 99) { System.out.println(a + "是二位数"); System.out.println("按逆序输出是" ); tn.converse(a); } else if(a >= 100 && a <= 999) { System.out.println(a + "是三位数"); System.out.println("按逆序输出是" ); tn.converse(a); } else if(a >= 1000 && a <= 9999) { System.out.println(a + "是四位数"); System.out.println("按逆序输出是" ); tn.converse(a); } else if(a >= 10000 && a <= 99999) { System.out.println(a + "是五位数"); System.out.println("按逆序输出是" ); tn.converse(a); }}public void converse(long l) { String s = Long.toString(l); char[] ch = s.toCharArray(); for(int i=ch.length-1; i>=0; i--) { System.out.print(ch[i]); }}}