Question

import java.util.Scanner;

public class PayAndGoParking
{

    public static void main(String Args[])
    {
       int choice=0;
       int numCars=0;
       String Plates[]=new String[50];
       String ccNumbers[]=new String[50];
       Scanner b = new Scanner(System.in);


        choice = printMenu();
        if(choice==1) {
            numCars=addCars(Plates,ccNumbers,numCars,b);
        }

    }

    public static int printMenu()
    {
        Scanner s = new Scanner(System.in);
        int choice;

        System.out.println("Welcome to Park and Go Parking");
        System.out.println("Park from 6 - Midnight for a flat fee of $4.00");

        System.out.println("1. Register your vehicle");
        System.out.println("2. Verify vehicle registration");

        System.out.print("Hello enter a Selection: ");
        choice = s.nextInt();

        if(choice==1) {
            System.out.println("Register your vehicle");
        }
        else {
            System.out.println("Verify your registration");
        }

        return choice;
    }


   public static int addCars (String [] plates,String [ ] ccNumbers, int numCars, Scanner keyboard)
   {
        Scanner s = new Scanner(System.in);


        System.out.println("Enter your plate number: ");
        plates[numCars]=s.nextLine();

        System.out.println("Enter your Credit Card Number ($4.00 charge): ");
        ccNumbers[numCars]=s.nextLine();



        System.out.println("Thank you, your plate " +plates[numCars]+ " has been added to the lot");

        numCars++;


        return numCars;



    }

所以我想要发生的事情是我想要用户输入的板号和ccCumber在addCars方法中存储在主方法中的板和ccNumber数组中。对不起，如果我听起来像我不知道我在说什么，我是编程和学习的新手。

Answer 1

GanGnaMStYleOverFlowErroR谈到了您提出的直接问题，但解决问题的更好方法是重新编写代码。您可以将它们设置为对象PayAndGoParking的属性，而不是将所有内容作为参数传递给您的方法。这使您可以通过将其范围更改为整个类来直接访问它们，而不仅仅是单个方法。

一般来说，你希望远离只是在所有东西上放下“静态”以使其工作。它是一个特殊的关键字有一个原因（并不是因为它只是使一切工作:)。查看下面的示例代码，看看我将如何做。随意提出任何问题。

import java.util.Scanner;
public class PayAndGoParking {
    private String Plates[];
    private String ccNumbers[];
    private int numCars;

    public static void main(String Args[])
    {
        PayAndGoParking park = new PayAndGoParking();
        //set the defaults
        park.Plates = new String[50];
        park.ccNumbers =new String[50];
        park.numCars=0;

        int choice = park.printMenu();

        if(choice==1)
            park.addCars();

        //since arrays start at 0, this will print out the first license and cc number added
        System.out.println(park.Plates[0]);
        System.out.println(park.ccNumbers[0]);
    }

    public int printMenu()
    {
        Scanner s = new Scanner(System.in);
        int choice;

        System.out.println("Welcome to Park and Go Parking");
        System.out.println("Park from 6 - Midnight for a flat fee of $4.00");

        System.out.println("1. Register your vehicle");
        System.out.println("2. Verify vehicle registration");

        System.out.print("Hello enter a Selection: ");
        choice = s.nextInt();

        if(choice==1)
            System.out.println("Register your vehicle");
        else
            System.out.println("Verify your registration");

        return choice;
    }

    public void addCars() {
        Scanner s = new Scanner(System.in);

        System.out.println("Enter your plate number: ");
        Plates[numCars]= s.nextLine();

        System.out.println("Enter your Credit Card Number ($4.00 charge): ");
        ccNumbers[numCars]= s.nextLine();

        System.out.println("Thank you, your plate " +Plates[numCars]+ " has been added to the lot");

        numCars++;
    }
}

Answer 2

String Plates[]=new String[50];
   String ccNumbers[]=new String[50];

您的Plates和ccNumber数组局部变量（方法变量）仅限于方法范围，即您无法在 main 之外访问它们方法。将它们设为静态实例变量，以便在类中的任何位置访问它们。

public class PayAndGoParking {
 static String Plates[]=new String[50];
 static  String ccNumbers[]=new String[50];
public static void main(String Args[]) {
 // code in your main
}
public static int addCars (String [] plates,String [ ] ccNumbers, int numCars, Scanner keyboard) { 
// you  can now access ccNumber and Plates array here.
}

可变范围：

静态变量 - 生活在班级本身的生活中。
Instanve变量 - 生活在班级生活的范围内
局部变量或方法变量 - 与方法一起生活。
块变量 - 仅在块中生存

如何在一个方法中从数组中获取值列表，并将这些值从我的main方法放入一个新数组中

2 个答案:

可变范围：