代码实现:取一个整数a从右端开始的4～7位

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

import java.util.Scanner; //取一个整数a从右端开始的4～7位。 public class Test {     public static void main(String[] args) {         Scanner sc = new Scanner(System.in);         System.out.println("请输入一个整数:");         String s = "";         Long ls = 0L;         while (true) {             s = sc.nextLine();             if (s.length() >= 7) {                 try {                     ls = Long.parseLong(s);                     break;                 } catch (NumberFormatException e) {                     System.out.println("内容非法,请重新输入一个整数:");                 }             } else {                 System.out.println("长度非法,请重新输入一个整数:");             }         }         StringBuffer sb = new StringBuffer();         sb.append(s);         sb.reverse();         String substring = sb.substring(3, 7);         System.out.println("取" + ls + "整数a从右端开始的4～7位:" + substring);     } }