java room management project
This room management project is suitable for java beginners. Although the function is not much, but the content is very complete!
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There are 5 floors in total, 10 rooms on each floor, marked with numbers 101-509;
It has four simple functions: check-in, check-out, search and exit;
public class Hotel {
static final int floor = 5;
static final int order = 10;
private static int countFloor;
private static int countOrder;
private static String[][] rooms = new String[floor][order];

//The main function represents the basic functions of the hotel, check-in, check-out, query and others;
public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    String temp = null;
    while(true){
        //Remind user to select input
        System.out.println("Please select input  in out search quit : ");
        temp = scan.next();
        int room = 0;
        if("in".equals(temp)){
            while(true){
                System.out.println("Please enter room number:");
                room = scan.nextInt();
                if(isRightRoom(room,1)){
                    break;
                }
            }
            System.out.println("Please enter a name:");
            String name = scan.next();
            if(in(room,name)){
                System.out.println("Congratulations on your successful stay");
                System.out.println(room + " : "+name);
            }
        }else if("out".equals(temp)){
            while(true){
                System.out.println("Please enter room number:");
                room = scan.nextInt();
                if(isRightRoom(room,0)){
                    break;
                }
            }
            if(out(room)){
                System.out.println("Check out successful, welcome to come next time");
            }
        }else if("search".equals(temp)){
            System.out.println("Please enter the room number to query(-1 Express all)");
            room = scan.nextInt();
            search(room);
        }else if("quit".equals(temp)){
            break;
        }else{
            System.out.println("Your input is wrong, please input again!");
        }
    }
}

//flag:1 check that the room number is entered correctly and no one is staying in 0 only check that the room number is entered correctly
private static boolean isRightRoom(int room,int flag) {
    //Check whether the room number is entered incorrectly
    countFloor = room / 100 - 1;
    countOrder = room % 100 - 1;
    if(countFloor < 0 || countFloor >= floor || countOrder < 0 || countOrder >= order ){
        System.out.println("Wrong room number entered");
        return false;
    }
    if(flag == 1){
        if(rooms[countFloor][countOrder] != null){
            System.out.println("The room has been checked in");
            return false;
        }
    }
    return true;
}

//in(room,name) countFloor: calculated floor countOrder: calculated room order 
private static boolean in(int room,String name){
    rooms[countFloor][countOrder] = name;
    return true;
}

//out(room),
private static boolean out(int room){
    //Check whether the room number is occupied
    if(rooms[countFloor][countOrder] == null){
        System.out.println("The room has not been checked in, check out is wrong");
        return false;
    }
    rooms[countFloor][countOrder] = null;
    return true;
}

//Hotel search function, search(room)
private static void search(int room){
    if(room == -1){
        int roomNum = 0;
        for(int i=0;i<floor;i++){
            for(int j=0;j<order;j++){
                roomNum = (i + 1) * 100 + j + 1;
                System.out.println(roomNum + "->" + 
                        (rooms[i][j] == null ? "empty" : rooms[i][j]));
            }
        }
    }else{
        //Check whether the room number is correct
        if(!isRightRoom(room,0)){
            System.out.println("Sorry, room input error!");               
        }else{
            System.out.println(rooms[countFloor][countOrder]);
        }
    }
}}