两道JAVA编程题不会 在线等！！急

Question

1、让用户从键盘输入用户名，取后两位，不足两位的，就取用户名本身，在控制台输出取出的名字+您好！
2、让学生输入学号，取出中间的第6位至8位表示班级编号，并输出
用JAVA编写

Answer 1

package test;

import java.util.Scanner;

public class Test3 {
    public static void main(String[] args) {
        Test3 t3 = new Test3();
        // t3.t1();
        t3.t2();
    }

    public void t1() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入用户名:");
        String name = scanner.next();
        if (name.length() > 2) {
            String lastName = name.substring(name.length() - 2);
            System.out.println(lastName + ",您好!");
        } else {
            System.out.println(name + ",您好!");
        }
        scanner.close();
    }

    public void t2() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入学号(长度10位):");
        String num = scanner.next();
        while (num.length() != 10) {
            System.out.println("请重新输入学号(长度10位):");
            num = scanner.next();
        }
        String classNum = num.substring(5, 8);
        System.out.println("班级号:" + classNum);
        scanner.close();
    }
}