How do I apply `ArrayList` of a `Room` to the `House` class?

I'm currently doing an assignment, where I have two classes Room and House. As a part of the assignment, I need to enable a House class to store the Rooms in ArrayList:

Implement a method to read in room information in the House class from the keyboard — this should call the Room constructor as required. Create a zero-argument House constructor to call this new method.

I apologize if this is vague or has been answered elsewhere, but having tried to understand the explanations on other similar queries, I don't know how to apply them to my situation.

How do I apply ArrayList of a Room to the House class?

House:

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

public class House {

private int idNum;
private static int internalCount = 0; 
private ArrayList rooms = new ArrayList();
private String address;
private int numRooms;
private String houseType; 

public House (String address, int numRooms, String houseType) {
idNum = internalCount++;

this.address = address;
this.numRooms = numRooms;
this.houseType = houseType;     
}


public House () {
int i = 0;  
idNum = ++internalCount;

Scanner scan = new Scanner(System.in);
scan.useDelimiter("\n");

System.out.println("Enter address of house:");   
address = scan.next();

System.out.println("Enter number of rooms:");   //Number of rooms in the House
numRooms = scan.nextInt();

 while (i < numRooms)  //This will loop until all rooms have been described
 {
 add.room = new Room[100]; //I understand this is incorrect but I don't know what  I should have in here
 i++;
 }

 System.out.println("Enter type of house:");
 houseType = scan.next();
 }
 public void addroom(String description, double length, double width)
 {

 }

 int getIdNum() {
 return idNum;
 }


 @Override
  
 public String toString()
 {
  String report = "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n";
  report += "Address: " + address + "\n";
  report += "No. of Rooms: " + numRooms + "\n";
  report += "House Type: " + houseType+ "\n";
  report += "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n";

  return report;
 }
 }

Room:

import java.util.Scanner;

public class Room {

private String description;
private double length;
private double width;

public Room (String description, double length, double width) {
this.description = description;
this.length = length;
this.width = width;     
}

public Room () {
Scanner scan = new Scanner(System.in);
scan.useDelimiter("\n");

System.out.println("Enter description of room:");
description = scan.next();

System.out.println("Enter length of room:");
length = scan.nextDouble();

 System.out.println("Enter width of room:");
 width = scan.nextDouble();
 }

 /*
 * Calculates and returns area of Room
 */
 public double getArea () {
 return length*width;
 }


 @Override
 public String toString() {
 return description + "- Length: " + length + "m; Width: " + width + 'm';
 }   
}

Since this is homework I wont solve it in entirety but give you a foundation to work from...

public class House {
  private List<Room> rooms;

  public House() {
    rooms = new ArrayList<Room>();
  }

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

  public int numRooms() {
    return rooms.size();
  }

  public Room getRoom(int roomNumber) {
    return rooms.get(roomNumber);
  }
}

public class Room {
  public Room(...) {
    ...
  }
}

Questions?