public class Test{

    // 测试方法

public static void main(String[] args) {

     //实例化对象，调用相关方法实现运行效果

        User a = new User("Lucy", "123456");

        User b = new User("Mike", "123456");

        a.display();

        b.display();

        System.out.println("=====================");

        UserManager u = new UserManager();

        System.out.println(u.checkUser(a,b));

    }

}

public class User{

    //定义属性用户名、密码

    private String username, password;

    public User(String username, String password){

        this.setUsername(username);

        this.setPassword(password);

    }

    public void setUsername(String username){

        this.username = username;

    }

    public String getUsername(){

        return username;

    }

    public void setPassword(String password){

        this.password = password;

    }

    public String getPassword(){

        return password;

    }

    public void display(){

        System.out.println("用户名："+this.getUsername());

        System.out.println("密码："+this.getPassword());

    }

}

public class UserManager{

    // 用户信息验证的方法

    public String checkUser(User one, User two) {

       // 判断用户名和密码是否为空，是否一致

        if(one.getUsername().length()==0 || two.getUsername().length()==0 ){

            return ("用户名为空");

        }else if(one.getPassword().length()==0 || two.getPassword().length()==0){

            return ("密码为空");

        }

        if(one.getUsername().equals(two.getUsername()) ||one.getPassword().equals(two.getPassword())){

            return ("用户名或密码不一致");

        }

        return "";

    }

}