Question

我最近才开始在uni的暑期课程中使用Java进行编码，因此我的代码知识和代码均未达到标准。

此作业要求我使用带有登录方法以及访问器和更改器的User类。一个具有动态大小的用户集合的EmailSystem类，一个将创建User对象并将其添加到用户列表的registerUser方法，以及一个将遍历用户列表的listUser方法。

EmailSystem类的代码：

public class EmailSystem {
   public static ArrayList<User> userList = new ArrayList<>();

   public static void registerUser(String firstname, String lastname, String username, String password) {
      User myUser = new User(firstname, lastname, username, password);
      userList.add(myUser);
      }

   public static void listUsers () {
      for (int i=0; i<userList.size(); i++)
      {
         System.out.println(userList.get(i));
      }
   }

   public static void main(String[] args) {
      registerUser("John", "Doe", "Username", "Password");
   }
}

用户类别的代码

import javax.swing.JOptionPane;
import java.util.*;

public class EmailSystem {
   public static ArrayList<User> userList = new ArrayList<>();

   public static void registerUser(String firstname, String lastname, String username, String password) {
      User myUser = new User(firstname, lastname, username, password);
      userList.add(myUser);
      }


   public static void listUsers () {
      for (int i=0; i<userList.size(); i++)
      {
         System.out.println(userList.get(i));
      }
   }

   public static void main(String[] args) {
      registerUser("John", "Doe", "Username", "Password");
      boolean hasExit = false;
      while (hasExit == false)
      {
         String options = "";
         options = JOptionPane.showInputDialog("The following actions are supported. Enter the code: \nA: Login\nB: Print Users\nC: Exit");
         if (options.equalsIgnoreCase ("A"))
         {
            String username = JOptionPane.showInputDialog("Username");
            String password = JOptionPane.showInputDialog("Password");
            // I would like to check whether the username and password submitted here are the same as the one used to register  
            // Use userLogin method here to compare the username and password that is inputted here and the username and password that was created when registering.
         }
         else if (options.equalsIgnoreCase ("B"))  
         {
            listUsers();
         }      
         else if (options.equalsIgnoreCase ("C"))
         {
            hasExit = true;
         }
      }  

   }
}

注册用户时，如何在创建的对象上运行userLogin方法？还是我应该完全做其他事情？

Answer 1

我认为 userLogin 方法在您的 EmailSystem 类中更为合理。并且userLogin方法应迭代userList以检查登录用户是否有效。代码可能像这样：

public class EmailSystem {
    public static ArrayList<User> userList = new ArrayList<>();

    public static void registerUser(String firstname, String lastname, String username, String password) {
        User myUser = new User(firstname, lastname, username, password);
        userList.add(myUser);
    }
    public static boolean userLogin(String _username, String _password) {
        boolean loginValid;
        User user = userList.stream().filter(o -> {
            if (o.getUser().equals(_username) && o.getPassword().equals(_password)) {
                return true;
            }
            return false;
        }).findFirst().orElse(null);
        if (user!=null)
            loginValid = true;
        else
            loginValid = false;
        return loginValid;
    }

    public static void listUsers () {
        for (int i=0; i<userList.size(); i++)
        {
            System.out.println(userList.get(i));
        }
    }

    public static void main(String[] args) {
        registerUser("John", "Doe", "Username", "Password");
        boolean b = userLogin("Username", "Password");
        System.out.println(b);
    }
}

和用户类别：

public class User {
    private String firstname;
    private String lastname;
    private String username;
    private String password;

    public User(String _firstname, String _lastname, String _username, String _password) {
        firstname = _firstname;
        lastname = _lastname;
        username = _username;
        password = _password;
    }
    public String getUser() {
        return username;
    }

    public String getPassword() {
        return password;
    }

    public String printName() {
        return firstname;
    }
    public void setUser(String sUser, String sPass) {
        username = sUser;
        password = sPass;
    }
    public void setName(String fName, String lName) {
        firstname = fName;
        lastname = lName;
    }
}

Answer 2

对于registerUser方法，将返回类型更改为User

 public static User registerUser(String firstname, String lastname, String 
  username, String password) {
      User myUser = new User(firstname, lastname, username, password);
      userList.add(myUser);
      return myUser;
      }

要验证用户名和密码，请检查以下逻辑，或者可以在userValidate方法中编写以下逻辑，然后在options =“ A”的情况下调用该方法

public static void main(String[] args) {
     User myuser= registerUser("John", "Doe", "Username", "Password");
      boolean hasExit = true;
      while (hasExit)
      {
         String options = "";
         options = JOptionPane.showInputDialog("The following actions are 
   supported. Enter the code: \nA: Login\nB: Print Users\nC: Exit");
         if (options.equalsIgnoreCase ("A"))
         {
            String username = JOptionPane.showInputDialog("Username");
            String password = JOptionPane.showInputDialog("Password");
            // I would like to check whether the username and password 
      // submitted here are the same as the one used to register  
            // Use userLogin method here to compare the username and password 
    //that is inputted here and the username and password that was created 
    //when registering
            if(myuser.getUsername().equals(username) && 
      myuser.getPassword.equals(password)) { 
                // this is for only created user object by using registerUser 
        // method
                // if you want to check in complete list need to iterate list 
            // here, by using for each or streams 
                System.out.println("user existed or success ");
                hasExit = false;
            }else {
                System.out.println("failed");
                hasExit = false;
            }
         }
         else if (options.equalsIgnoreCase ("B"))  
         {
            listUsers();
           hasExit = false;
         }      
         else if (options.equalsIgnoreCase ("C"))
         {
            hasExit = false;
         }
      }  

   }

但是您仍然可以使此代码更简洁，也可以编写开关大小写而不是while循环

推荐的方法是在方法内部编写逻辑并在main中调用该方法

使用其他方法的对象实例

2 个答案: