自己写的代码：

import java.util.Scanner;
public class practice {
    static String rightUsername = "zhangsan";
    static String rightPassword = "123456";

    public static void main(String[] args) {
        //读题拆解法
        //1、定义两个变量，记录正确的用户名和密码
        if(name()==3) {
            System.out.println("登陆系统失败");
            return;
        }else{
            password();
        }
    }
    public static int  name() {
        //模拟实现用户登录系统
        Scanner input = new Scanner(System.in);
        int count = 0;
        for (int i = 0; i < 3; i++) {
            System.out.println("输入用户名：");
            String userName = input.next();
            if (userName.equals(rightUsername)) {
                System.out.println("用户名输入正确，请输入密码：");
                break;
            } else {
                System.out.println("输入错误，请重新输入");
                count++;
            }
        }
        return count;
    }
    public static void password() {
        Scanner input = new Scanner(System.in);
        for (int i = 0; i < 3; i++) {
            System.out.println("输入密码：");
            String password = input.next();
            if (password.equals(rightPassword)) {
                System.out.println("密码输入正确，登陆系统成功：");
                return;
            } else {
                System.out.println("输入错误，请重新输入");
            }
        }
        System.out.println("登陆系统失败");
    }
}

代码运行结果：

视频讲解代码：