java - 图书馆系统登录 退出

Question

class Test{
    public static void main(String args[])
    {
        Patron list[] = new PatronData().getPatronData();

        /*for(Patron p: list)
        {
            System.out.println(p);
        }*/
    }
    }


    class PatronData{
    //Patron patron[] = {new     Patron("Daniel","A001","15WAD00001","A4701,Jalan Kepong,     Pahang","JK01",0.00,"012-8765432"),
    //               new Patron("Chiam","A002","15WAD00002","A4702,Jalan     Akar,Pahang","JK02",0.00,"0102288554")};
    Patron patron[] = new Patron[2];

    public Patron[] getPatronData()
    {
        patron[0] = new Patron("Daniel","A001","15WAD00001","A4701,Jalan     Kepong, Pahang","JK01",0.00,"012-8765432");
        patron[1] = new Patron("Chiam","A002","15WAD00002","A4702,Jalan     Akar,Pahang","JK02",0.00,"0102288554");
        return patron;
    }
}

class Patron{
    private String userName;
    private String password;
    private String userCode;
    private String streetAddress;
    private String postCode;
    private double overdueBalance;
    private String phoneNumber;

    Patron(String userName[], String password[], String userCode, 
    String streetAddress, String postCode, double overdueBalance, String     phoneNumber)
    {
        this.userName = userName;
        this.password = password;
        this.userCode = userCode;
        this.streetAddress = streetAddress;
        this.postCode = postCode;
        this.overdueBalance = overdueBalance;
        this.phoneNumber = phoneNumber;

        int logNMatch = 0;

        Scanner scan = new Scanner(System.in);
        do{

            System.out.print("Please Enter Your User Name > ");
            String inputUserName=scan.nextLine();
            System.out.println();
            System.out.print("Please Enter Your Password  > ");
            String inputPassword = scan.nextLine();

            if(userName.compareTo(inputUserName) == 0 &&     password.compareTo(inputPassword) == 0)
            {
                System.out.println("Logging Successful");
                System.out.print("\n\n");

            }
            else
            {
                System.out.println("Loging fail");
                System.out.println("Please again later");
                logNMatch++;
            }
        }while(logNMatch > 0);
    }
    }

大家好，我正在学习文凭级别的 Java。我有个问题。拜托，我不知道为什么我不能立即登录“Chiam帐户”，我期望的是当我登录时编译器会自动检查登录详细信息是否与图书馆系统中的数据匹配。

Answer 1

您正在构造函数内请求登录信息。这意味着每当您创建新的Patron时，它都会提示您使用该用户的信息登录。

相反，删除 do/while 循环中的所有内容，并添加一个类似 loginFromLibrary() 的方法，该方法将提示用户输入名称和密码。然后检查所有Patron，看看他们的名字是否与给定的用户名匹配。然后只需确保用户名与密码匹配即可。

此示例需要一些 getter(getPassword() 和 getUsername()):

public void loginFromLibrary(Patron[] patrons){
    Scanner scan = new Scanner(System.in);
    while (true){
        // get usernmae
        System.out.println("Username > ");
        String username = scan.nextLine();
        Patron user = null;
        // check array to see if username exists
        for (Patron p : patrons){
            if (p.getUsername().equals(username)){
                user = p;
                break;
            }
        }
        if (user == null){
            // username not found
            System.out.println("Username not found");
            continue;
        }
        // get password
        System.out.println("Password > ");
        String pass = scan.nextLine();
        // check password
        if (pass.equals(user.getPassword())){
            // logged in
            break;
        } else {
            // wrong password
        }
    }
    scan.close();
}