Question

我是Java新手，我尝试编写一个简单的房间预订程序。

这是我的计划：

将会有一个名为Booking的课程。它将要求用户输入房间ID来预订房间，用户可以按x终止程序。

我想要另一个名为RoomDB的课程。我将使用arraylist来存储房间ID。

我想我也需要构造函数，所以我有另一个名为Room的类。

我的想法是，当程序运行时，它将显示可供用户选择的房间ID。如果用户输入了错误的房间ID，程序将显示错误消息并要求用户再次输入。

如果用户输入了正确的房间ID并且房间ID可用，它将向用户显示成功消息。

如果用户输入了正确的房间ID且房间ID已经预订，则会要求用户再次输入。

这就是我的想法，我开始编写代码。

这是我的三个类的代码

Booking.java

package test;

import java.util.Scanner;

public class Booking 
{
static RoomDB roomDB = new RoomDB();

public static void main(String[] args) {
    String roomID;      
    Room room;  
    Scanner inputID = new Scanner(System.in);

        while(true){

            System.out.println("Please choose the room you want to book \n"+getRoomList(roomDB));

            while(true){
                roomID = inputID.nextLine();
                if(roomID.equals ("x")){
                    break;
                }

                if(getRoom(roomID) == null){

                    System.out.println("The room ID is incorrect, please enter again or enter x to quit");

                }
                else{

                    room = getRoom(roomID);

                    if(!room.isBooked()){
                        System.out.println("Book successfully");
                        break;
                    }
                    else{
                        System.out.println("please enter the room ID again or enter x to quit");
                    }
                }

            }

        }

    }

public static String getRoomList(RoomDB roomDB)
{

    String roomList = "";
    for(Room r:roomDB.getRoom())
    {

        if(!r.isBooked())
        {
            roomList = roomList+r.getRoomID()+" is free"+"   ";
        }
        else
        {
            roomList = roomList+r.getRoomID()+" has been booked ";
        }

    }
    return roomList;
}


public static Room getRoom(String roomID){

    for(Room r:roomDB.getRoom()){

        if(r.getRoomID()==roomID){

            return r;

        }

    }
    return null;

}
}

RoomDB.java

package test;

import java.util.ArrayList;

public class RoomDB 
{
private ArrayList<Room> room;
private String[] roomID = {"Room1","Room2"};

RoomDB(){

    room = new ArrayList<Room>();                     
    for(int i=0;i<roomID.length;i++)
    {
        addRoom(new Room(roomID[i]));
    }

}

public void addRoom(Room addRoom){
    room.add(addRoom);
}

public ArrayList<Room> getRoom(){
    return room;
}
}

Room.java

package test;

public class Room 
{
private String roomID  = null;
private boolean booked = false;

Room(String roomID)
{
    this.roomID = roomID;
}

String getRoomID()
{
    return roomID;
}

void cancel()
{
    booked = false;
}


boolean isBooked()
{
    return booked;
}

}

我检查过没有语法错误，但程序无法正常运行。

问题是程序一直要求用户输入房间ID，即使房间ID是正确的。例如，用户输入Room1，程序仍然要求输入。

我想知道哪个班级会导致问题。

如果有人能就此问题提出建议，我将不胜感激。

Answer 1

这是完美答案，看到这只是复制它并运行下面的代码，请根据需要相应地删除修改到您的包/类名称，

忘记在分配房间后设置为真，如果房间似乎是免费的，那么分配并将其标记为BOOKED-＆gt; true。

package roombooking;

import java.util.ArrayList;
import java.util.Scanner;

class Room 
{
    private String roomID  = null;
    private boolean booked = false;

    Room(String roomID)
    {
        this.roomID = roomID;
    }

    String getRoomID()
    {
        return roomID;
    }

    void cancel()
    {
        booked = false;
    }


    boolean isBooked()
    {
        return booked;
    }

    public void setBooked(boolean booked) {
        this.booked = booked;
    }


}

class RoomDB 
{
    private ArrayList<Room> room;
    private String[] roomID = {"Room1","Room2"};

    RoomDB(){

        room = new ArrayList<Room>();                     
        for(int i=0;i<roomID.length;i++)
        {
            addRoom(new Room(roomID[i]));
        }

    }

    public void addRoom(Room addRoom){
        room.add(addRoom);
    }

    public ArrayList<Room> getRoom(){
        return room;
    }
}

public class Booking {

    static RoomDB roomDB = new RoomDB();

    public static void main(String[] args) {
        String roomID;      
        Room room;  
        Scanner inputID = new Scanner(System.in);

        while(true){

            System.out.println("Please choose the room you want to book \n"+getRoomList(roomDB));

            while(true){
                System.out.println("Enter your Room no. : (Enter x for quite ) : ");
                roomID = inputID.nextLine();
                System.out.println("X : " + roomID.equals("x"));
                if(roomID.equals("x")){
                    System.out.println("Break");
                    break;
                }

                if(getRoom(roomID) == null){

                    System.out.println("The room ID is incorrect, please enter again or enter x to quit");

                }
                else{

                    room = getRoom(roomID);

                    if(!room.isBooked()){
                        System.out.println("Book successfully");
                        room.setBooked(true);
                        break;
                    }
                    else{
                        System.out.println("please enter the room ID again or enter x to quit");
                    }

                }

            }

        }

    }

    public static String getRoomList(RoomDB roomDB)
    {

        String roomList = "";
        for(Room r:roomDB.getRoom())
        {

            if(!r.isBooked())
            {
                roomList = roomList+r.getRoomID()+" is free"+"   ";
            }
            else
            {
                roomList = roomList+r.getRoomID()+" has been booked ";
            }

        }
        return roomList;
    }


    public static Room getRoom(String roomID){

        for(Room r:roomDB.getRoom()){

            if(r.getRoomID().equals(roomID)){
                System.out.println("r.getRoomID : " + r.getRoomID() + "  AND user.roomID :" + roomID);
                return r;
            }

        }
        return null;

    }

}

已编辑：

在这里，

if(!room.isBooked()){
System.out.println("Book successfully");
room.setBooked(true); // this line does, booked room, after booked once it won't assign to any one else.
break;

}

Answer 2

public static Room getRoom(String roomID){

for(Room r:roomDB.getRoom()){

    if(r.getRoomID().equals(roomID)){ //Old : r.getRoomID()==roomID

        return r;

    }

}
return null;

}

对于比较字符串，请始终使用等于。

Answer 3

从表面看，你的问题出现在你将字符串与＆＃34; ==＆＃34;进行比较的那一刻。运营商。这是不可能的，因为＆＃34; ==＆＃34;运算符尝试识别两个对象是否相等，而不是它们各自的值。您可以在此处获得有关String比较如何工作的更好和完整的解释：How do I compare strings in Java?

作为您问题的快速妥善解决方法，请使用：

if(r.getRoomID().equals(roomID))
{ 
    return r;
}

Answer 4

我还建议您在相同的情况下比较字符串（在Booking.java中的2个位置）：

if (roomID.equalsIgnoreCase("x"))

以及

if (r.getRoomID().equalsIgnoreCase(roomID))

希望有所帮助。

房间预订计划

4 个答案: