java如何使用方法解决：锁定帐户三次后？

Question

我正在尝试创建一个使用方法锁定/解锁帐户的程序。 这是我的程序，但当我试着运行它时，它说我询问用户名和密码的方法中的参数不能为空

我是一个初学者，刚刚学会了如何使用方法，所以如果有人能帮助解释这个程序的错误，那就太好了

我还试图创建一个方法来锁定帐户后，三次尝试使用循环，但我被卡住了。请给我一些建议，谢谢

//Lock account after n=3 using methods
//using Methods created

import java.util.Scanner;

public class Lock_Methods{
    public static void main(String [] args){

        String user_name = question();
        String pass_word = ask();

        int result = testing(user_name, pass_word);

        if (result == 0){
            System.out.println("Welcome");
        }
        else
            System.out.println("Locked");


    } //end of main


    //2. method for asking username
    public static String question(){
        Scanner input = new Scanner (System.in);

        System.out.println("Enter username: ");
        String username = input.nextLine();

        return username;
    }

    //3. method for asking password
    public static String ask(String password){
        Scanner input = new Scanner (System.in);

        System.out.println("Enter Password: ");
        password = input.nextLine();

        return password;

    }


    //4. method for testing whether username and password are true
    public static int testing(String inputname, String inputpw){
        int result = 0;
        String username = "edu";
        String password = "12345";

        if (!(username.equals(inputname)) || ! (password.equals(inputpw)))
            return 1;
        else
            return 0;

        return result; //return statment

    }



} //end of class

Answer 1

从public static String ask(String password)中删除String password

当您在String pass_word = ask();调用ask方法时，您没有在ask()中传递任何参数，但是您的方法声明中有一个参数String password。因为您没有传递参数，所以它会给您该错误

这就是你的ask()方法应该是这样的：

public static String ask(){
    Scanner input = new Scanner (System.in);

    System.out.println("Enter Password: ");
    password = input.nextLine();

    return password;
}

就三次尝试而言，试着运行这个。我在这里也做了上面提到的更改，所以只需运行这个，看看它是否有效：

import java.util.Scanner;

public class Lock {
    public static void main(String [] args){

        String user_name = question();
        String pass_word = ask();

        int count = 0;

        while (count < 4) {
            int result = testing(user_name, pass_word);

            if (result == 0) {
                System.out.println("Welcome");
            }
            count++;
        }

        if (count > 3) {
            System.out.println("Locked");
        }

    } //end of main 

    //2. method for asking username
    public static String question(){
        Scanner input = new Scanner (System.in);

        System.out.println("Enter username: ");
        String username = input.nextLine();

        input.close();

        return username;
    }

    //3. method for asking password
    public static String ask(){
        Scanner input = new Scanner (System.in);

        System.out.println("Enter Password: ");
        String password = input.nextLine();

        input.close();

        return password;

    }


    //4. method for testing whether username and password are true
    public static int testing(String inputname, String inputpw){
        int result = 0;
        String username = "edu";
        String password = "12345";

        if (!(username.equals(inputname)) || ! (password.equals(inputpw)))
            result = 1;

        return result; //return statment

    }
}