类，对象和方法在Java中有用

Question

由于公共类HotelManagement和公共类Room的问题，NetBeans不会让我运行我的程序。任何人都可以帮我解决这个问题所以我的程序将顺利运行。感谢

public class HotelManagement {

    public static void main(String[] args) {
        Room room1 = new Room(3348, 80, "Single Bed"); 
        Room room2 = new Room(3347, 90, "Double Bed"); 
        Room room3 = new Room(3346, 140, "Suite");
        room1.Book(); 
        room2.printRoomInfo(); 
        room3.setRate(180); 
        room1.Release(); 
        room1.printRoomInfo(); 
        room3.printRoomInfo();
    }

    }



    public class Room {


    private final int number;
    private final String type;
    private int rate;
    private boolean isBooked;


    public Room(int number, int rate, String type) {

        this.number = number;
        this.type = type;
        this.rate = rate;
        this.isBooked = false; 
    }


    public void Book() {
        System.out.println("Room " + this.number + " has successfully been booked.");
        this.isBooked = true;
    } 

    // This method "releases" the booking on the room by setting the instance variable isBooked to false
    public void Release() {
        System.out.println("Room " + this.number + " has successfully been released.");
        this.isBooked = false;
    }

    // Print basic info about the current Room objects state 
    public void printRoomInfo() {
        String state; 
        if (this.isBooked == true) { 
            state = "Unavailable"; 
        }

        else { 
            state = "Available";
        }

        System.out.println("Room " + this.number + " is a " + this.type + ". Rate is: " + this.rate + "$ per night. " + state + ".");

    }


    public void setRate(int newRate) {
        this.rate = newRate;
    }
    }

Answer 1

如果你想将两个类放在一个你需要的文件中：

1. 在HotelManagement类中移动Room class声明
2. 将其设为静态，例如public static class Room {

所以，最终的结构将是这样的：

public class HotelManagement {
    public static void main(String[] args) {
...
    }

    public static class Room {
....
    }
}

Answer 2

在.java文件中只能有一个公共类，它将是具有public static void main的类。如果在同一个文件中的其他类不能公开。

public class HotelManagement {

    public static void main(String[] args) {
        Room room1 = new Room(3348, 80, "Single Bed"); 
        Room room2 = new Room(3347, 90, "Double Bed"); 
        Room room3 = new Room(3346, 140, "Suite");
        room1.Book(); 
        room2.printRoomInfo(); 
        room3.setRate(180); 
        room1.Release(); 
        room1.printRoomInfo(); 
        room3.printRoomInfo();
    }

    }



     class Room {


    private final int number;
    private final String type;
    private int rate;
    private boolean isBooked;


    public Room(int number, int rate, String type) {

        this.number = number;
        this.type = type;
        this.rate = rate;
        this.isBooked = false; 
    }


    public void Book() {
        System.out.println("Room " + this.number + " has successfully been booked.");
        this.isBooked = true;
    } 

    // This method "releases" the booking on the room by setting the instance variable isBooked to false
    public void Release() {
        System.out.println("Room " + this.number + " has successfully been released.");
        this.isBooked = false;
    }

    // Print basic info about the current Room objects state 
    public void printRoomInfo() {
        String state; 
        if (this.isBooked == true) { 
            state = "Unavailable"; 
        }

        else { 
            state = "Available";
        }

        System.out.println("Room " + this.number + " is a " + this.type + ". Rate is: " + this.rate + "$ per night. " + state + ".");

    }


    public void setRate(int newRate) {
        this.rate = newRate;
    }
    }

Answer 3

每个源文件只能有一个公共类。因此，要使代码正常工作，您需要执行其中一项操作

1. 将每个公共类放在单独的源文件中。无论包装是什么，都可以从任何地方访问公共类。
2. 删除课程public
的Room访问修饰符

另一种方法是使类Room保持静态并将其放在类HotelManagement中。但是，当你非常擅长基本概念时，我建议你学习Java中的静态嵌套类和内部类等高级概念。