java中reserve（list）

在Java中，List没有reserve()方法。但是，可以使用ArrayList的ensureCapacity()方法来指定List的容量，以便在添加元素时不必频繁地扩容。该方法的语法如下：

public void ensureCapacity(int minCapacity)

其中，minCapacity表示希望List能够容纳的最小元素数量。如果List当前的容量小于minCapacity，则该方法会增加List的容量，否则该方法不会有任何影响。

需要注意的是，调用ensureCapacity()方法并不会改变List中元素的数量，只是为List分配了更多的内存空间。如果需要在List中添加更多的元素，则可以直接使用add()方法添加，List会自动扩容。

相关问题

机票订票系统java代码

机票订票系统的Java代码可以包含以下几个主要功能：

1. 用户注册和登录功能：包括用户注册账号和密码，以及用户登录功能。

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

    public User(String username, String password) {
        this.username = username;
        this.password = password;
    }

    // Getter and Setter methods
    // ...
}

public class UserRegistration {
    public void register(String username, String password) {
        // Code to register new user
    }
}

public class UserLogin {
    public boolean login(String username, String password) {
        // Code to check if username and password are correct
        return true;
    }
}

2. 机票查询功能：根据用户输入的出发地、目的地和日期，查询可用的机票。

public class Flight {
    private String departure;
    private String destination;
    private String date;
    private double price;

    public Flight(String departure, String destination, String date, double price) {
        this.departure = departure;
        this.destination = destination;
        this.date = date;
        this.price = price;
    }

    // Getter methods
    // ...
}

public class FlightSearch {
    public List<Flight> search(String departure, String destination, String date) {
        // Code to search for available flights
        return flights;
    }
}

public class TicketReservation {
    public void reserveTicket(Flight flight) {
        // Code to reserve ticket for the flight
    }
}

3. 机票预订功能：根据用户选择的机票，进行预订并生成订单。

public class Order {
    private User user;
    private Flight flight;
    private Date orderDate;
    private String status;

    public Order(User user, Flight flight, Date orderDate, String status) {
        this.user = user;
        this.flight = flight;
        this.orderDate = orderDate;
        this.status = status;
    }

    // Getter methods
    // ...
}

public class OrderReservation {
    public Order reserveOrder(User user, Flight flight) {
        // Code to create order reservation
        return order;
    }
}

public class OrderManagement {
    public void cancelOrder(Order order) {
        // Code to cancel the order
    }
}

以上代码只是简单示例，实际的机票订票系统需要根据具体需求进行设计和实现。

java实现多人预约座位的程序

以下是一个简单的Java程序，用于实现多人预约座位的功能：

import java.util.*;

public class SeatReservation {
    private static int ROWS = 10;
    private static int SEATS_PER_ROW = 10;
    private static int AVAILABLE_SEATS = ROWS * SEATS_PER_ROW;
    private static boolean[][] seats = new boolean[ROWS][SEATS_PER_ROW];

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        while (true) {
            System.out.println("Welcome to Seat Reservation System!");
            System.out.println("Please enter the number of seats you want to reserve (0 to exit):");
            int numSeats = scanner.nextInt();
            if (numSeats == 0) {
                break;
            }
            if (numSeats > AVAILABLE_SEATS) {
                System.out.println("Sorry, there are not enough seats available!");
                continue;
            }

            List<String> reservedSeats = new ArrayList<>();
            for (int i = 0; i < numSeats; i++) {
                System.out.println("Please enter the row and seat number you want to reserve (e.g. 1A):");
                String input = scanner.next();
                int row = Integer.parseInt(input.substring(0, 1)) - 1;
                int seat = input.charAt(1) - 'A';
                if (row < 0 || row >= ROWS || seat < 0 || seat >= SEATS_PER_ROW || seats[row][seat]) {
                    System.out.println("Sorry, the seat you entered is not available!");
                    i--;
                    continue;
                }
                seats[row][seat] = true;
                reservedSeats.add(input);
            }

            System.out.println("Congratulations! Your seats have been reserved:");
            for (String seat : reservedSeats) {
                System.out.print(seat + " ");
            }
            System.out.println();
            AVAILABLE_SEATS -= numSeats;
        }

        System.out.println("Thank you for using Seat Reservation System!");
    }
}

该程序使用一个二维数组来存储座位的预订情况。当用户输入要预订的座位数量时，程序会逐个询问用户要预订的具体座位，并检查座位是否可用。如果座位已经被预订或者超出了剩余可用座位的数量，程序会提示用户重新输入。如果所有座位都成功预订，程序会输出预订的座位信息，并更新剩余可用座位的数量。用户可以通过输入0来退出程序。