Question

The management of a motel wishes to keep track of the occupancy of rooms in the motel. Each room is represented by an object of the following Room class.

public class Room
{
  private int roomNumber;
  private boolean occupied;
  private String bookingName;
 
 
  /** Attempts to check a new guest into the room. If the room is not occupied (the 
    * variable occupied is false), changes bookingName to name and sets
    * occupied to true.
    * Otherwise does not change the values of the member variables.
    * @param name the name of the guest checking in as a String
    * @return true if the check-in was successful and bookingName was changed
    * 		false otherwise
    */
  public boolean checkInNewGuest(String name)
  {  /* implementation not shown */  }
 
 
  /** @return the room number
	*/
  public int getNumber()
  {  return roomNumber;  }

  /** @return true if the room is occupied; false otherwise.
	*/
  public boolean isOccupied()
  {  return occupied;  }
 
  // There may be instance variables, constructors and methods that are not shown.
}

The following OccupancyInfo class creates and maintains a database of the rooms in the hotel. The rooms are not sorted in the database, but no two rooms have the same number.

public class OccupancyInfo
{
  private ArrayList rooms;
  // no two Room objects in rooms have the same room number
 
 
  /** Attempts to check-in a new guest into a given room number. If a room exists in
    * the database with the room number requested, and the room is unoccupied, a guest
    * with the name given is checked-in to that room: the room is marked as occupied,
    * and the bookingName variable in the Room object is set to the name given.
    * @param name the name of the guest attempting to check-in
    * @param number the room number into which the guest is to be checked-in
    * @return -1 if no room with the requested number exists;
    * 		0 if the room requested is occupied;
    * 		1 if the check-in is successful
    */
  public int checkIn(String name, int number)
  {  /* to be implemented in part (a) */  }


  /** Returns an ArrayList containing the number of every room which is not occupied
    * in the order in which these appear in the ArrayList rooms.
    */
  public ArrayList availableRoomNumbers()
  {  /* to be implemented in part (b) */  }

  // There may be instance variables, constructors and methods that are not shown.
}

(a) Write the OccupancyInfo method checkIn. This method attempts to check a new guest into a given room number. If no Room object exists in the list rooms with that number, no data is changed and the method returns -1. If the room with that number is occupied (the variable occupied is true), no data is changed and the method returns 0. If the room with that number is unoccupied, the guest is checked-in: the room is marked as occupied, and the bookingName variable in the Room object is set to the name given. If a guest is successfully checked-in the method returns 1. Complete method checkIn below.

/** Attempts to check-in a new guest into a given room number. If a room exists in
  * the database with the room number requested, and the room is unoccupied, a guest
  * with the name given is checked-in to that room: the room is marked as occupied,
  * and the bookingName variable in the Room object is set to the name given.
  * @param name the name of the guest attempting to check-in
  * @param number the room number into which the guest is to be checked-in
  * @return -1 if no room with the requested number exists;
  * 		0 if the room requested is occupied;
  * 		1 if the check-in is successful
  */
public int checkIn(String name, int number)

(b) Write the OccupancyInfo method availableRoomNumbers. This method returns an ArrayList containing the number of every room which is not occupied in the order in which these appear in the ArrayList rooms.

Complete method availableRoomNumbers below.

/** Returns an ArrayList containing the number of every room which is not occupied
  * in the order in which these appear in the ArrayList rooms.
  */
public ArrayList availableRoomNumbers()

Answer 1

For question 1, the method checkIn would be as follows:

public boolean checkIn(String name){

if(this.occupied==true){

return false;

}

else{

this.bookingName=name;

this.occupied=true;

return true;

}

}

As you can see if the value of the boolean variable "occupied" is true then the if statement is executed. If statement is executed when the room is already occupied and thus false is returned according to the question. If the value of occupied is false, the else statement is executed.

For Question 2, the following is the code for the checkIn method:

public int checkIn(String name,int number){

boolean RoomPresent=false;

int index=0;

for(Room i : rooms){

if(i.roomNumber=number){

RoomPresent=true;

break;

}

index++;

}

if(RoomPresent==false){

return -1;

}

else{

if(rooms.get(index).checkIn(name)){

return 1;

}

else{

return 0;

}

}

}

In the second question first we run a for loop for each object present in the arraylist rooms. We create two variables, one boolean named RoomPresent which is initialized to false. This variable is set to true when one of the rooms in the ArrayList rooms has the room to be booked. Along with that, we track the index of that room by incrementing a variable index, which is initialized to 0. After every iteration of the loop, the value of the variable index gets incremented by 1 and thus it gets the index of the room we're looking for. Otherwise, the value of this variable is not important. If RoomPresent is false at the end of the loop, that means that the room is not present in the ArrayList rooms and thus -1 is returned. Otherwise, if RoomPresent is true, we call the checkIn function of the room object with index "index" in the ArrayList rooms, which returns true if the room is allotted, otherwise, it returns false. If true is returned, it means that the room is successfully allotted and we return 1. If not 0 is returned.