Question

我对Java还是很陌生，但是我在c ++和python方面有不错的经验。因此，我正在做一个问题，即即时通讯需要实施飞机预订系统，该系统可以执行以下操作-

1。将所有座位初始化为未占用（假）

2。要求输入（生态或一流）

3。检查座位是否未被占用

4。如果没有座位，请分配座位，否则寻找下一个座位

5。如果预订了经济舱座位，请询问用户是否想升至头等舱

6。如果用户为否定，则显示味精“下一平面在3小时内”

但是

package oop;
import java.util.Arrays;
import java.util.Scanner;

public class AirplaneBooking {

    private final static int MAX_ECO_SEATS = 5;
    private final static int MAX_FIRST_CLASS_SEATS = 3;
    private final static boolean[] ECO_SEATS = new boolean[MAX_ECO_SEATS];
    private final static boolean[] FIRST_CLASS_SEATS = new boolean[MAX_FIRST_CLASS_SEATS];
    private static int current_eco_seat = 0;
    private static int current_first_class_seat = 0;

    public static void initialilze_seats(boolean[] first_class_seats, boolean[] eco_class_seats){
        Arrays.fill(first_class_seats, Boolean.FALSE);
        Arrays.fill(eco_class_seats, Boolean.FALSE);
    }

    public static void display(boolean[] seats){
        System.out.print("[");
        for(boolean seat : seats){
            System.out.print(seat + ",");
        }
        System.out.println("]");
    }

    public static void book_seat(boolean [] seats, int current_seat){
        seats[current_seat] = true;
        current_seat++;
        System.out.println(current_seat);
    }


    public static int user_input() {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter 1 for Economy class or 2 for First class : ");
        int user_seat_prefrence = input.nextInt();
        if (user_seat_prefrence == 1){
            if(current_eco_seat < MAX_ECO_SEATS){
                book_seat(ECO_SEATS, current_eco_seat);
            }
            else{
                System.out.println("Looks like eco seats are full, would you like to book for first class insted(1/0) ?");
                Scanner next_input = new Scanner(System.in);
                int user_next_seat_prefrence = next_input.nextInt();
                if (user_next_seat_prefrence == 1){
                    book_seat(FIRST_CLASS_SEATS, current_first_class_seat);
                    user_seat_prefrence = 2;
                }
                else{
                    System.out.println("next flight leaves in 3 hrs");
                }
            }

        }

        else if  (user_seat_prefrence == 2){
            if (current_first_class_seat < MAX_FIRST_CLASS_SEATS){
                book_seat(FIRST_CLASS_SEATS, current_first_class_seat);
            }
            else{
                System.out.println("Looks like first class seats are full, would you like to book economy instead?(1/0)");
                int user_next_seat_prefrence = input.nextInt();
                if (user_next_seat_prefrence == 1){
                    book_seat(ECO_SEATS, current_eco_seat);
                    user_seat_prefrence = 1;
                }
                else{
                    System.out.println("Next flight leaves in 3hrs");
                }

            }
        }

        else {
            System.out.println("Enter valid option");
        }

        return user_seat_prefrence;
    }

    public static void print_boarding_pass(int user_seat_prefrence){
        if (user_seat_prefrence == 1){
            System.out.println("eco");
            System.out.println(current_eco_seat - 1);
        }
        else{
            System.out.println("first class");
            System.out.println(current_first_class_seat - 1); 
        }
    }
    public static void main(String args[]){
        initialilze_seats(FIRST_CLASS_SEATS, ECO_SEATS);
        display(FIRST_CLASS_SEATS);
        display(ECO_SEATS);
        while(true){
            int user_seat_prefrence = user_input();
            print_boarding_pass(user_seat_prefrence);    
            display(FIRST_CLASS_SEATS);
            display(ECO_SEATS);
            System.out.print("book another seat:");
            Scanner choice = new Scanner(System.in);
            boolean book_another_seat = choice.nextBoolean();
            if (book_another_seat == false)
                break;
         
        }
    }

}

此代码存在的问题是，例如，生态舱位（例如）是否已满，该程序应该询问我是否要预订头等舱并等待输入，如果按1应该在头等舱预定，但是程序不会等待我的输入，而是继续执行else语句。

此外，我使用static变量current_eco_seat和current_first_class_seat来跟踪当前预订的座位，并将该静态变量传递给book_seat函数，然后，程序会预订座位并递增current_eco_seat或current_first_class_seat（取决于通过哪个座位），以便可以在下一次交互中预定下一个座位。但是静态变量根本不会增加。

这些是我程序唯一的问题。

感谢您的帮助，谢谢

Answer 1

当Java通过值调用方法时，

关于静态的问题是您将current_seat的值传递给book_seat方法，因此更改值不会影响从该方法返回后的变量。

要解决此问题，只需调用方法，而不传递您的静态变量。它是静态的，因此您可以从任何地方访问它。

即：

public static void book_seat(boolean [] seats){
        seats[current_seat] = true;
        current_first_class_seat++;
        System.out.println(current_seat);
    }

Answer 2

签出流

不确定您的问题是否与“静态”变量有关，或更与“如何处理输入流？”有关。

关于：

如果我按1，它应该在头等舱预定，但是程序不会等待我的输入，而是继续执行else语句。

在重新阅读之前，您应该考虑“刷新”输入流。 flush-clear-system-in-stdin-before-reading

方法参数用法

另一方面，这种方法是错误的

    public static void book_seat(boolean [] seats, int current_seat){
    seats[current_seat] = true;
    current_seat++;
    System.out.println(current_seat);
}

此命令无效，但会向用户打印信息。您在调用方“ current_eco_seat”中使用的变量完全不会更改。

Answer 3

您无需坚持要增加确切的变量，只需执行以下操作：

使name返回增加的值

series.name = "Series #1"

将返回值设置为book_seat()或public static int book_seat(boolean [] seats, int current_seat) { seats[current_seat] = true; System.out.println(current_seat + 1); return current_seat + 1; }

current_first_class_seat

然后，您可以按照先前的意图使用current_eco_seat进行经济舱和头等舱预订。

我如何在Java中增加静态变量

3 个答案: