Please implement a class, ApartmentDirectory, to model a list, indexed by apartmentNumber, of Familys living within an apartment building. You are provided with the Family class specification which describes simply objects composed of only a familyName and a size of the family.

The ApartmentDirectory class should have the following properties:

• It should model a fixed number of whole apartments, numbered 0 through some maximum numberOfApartments. This size should be fixed when the ApartmentDirectory is initialized.
  
  
• It should be possible to recordAFamily in the directory. This associates a Family object with a particular apartmentNumber. Apartments are numbered 0 through numberOfApartments-1. Recording a Family in the directory should destroy any prior association between a Family and the same apartmentNumber, if any.
  
  
• It should be possible to getTheApartmentNumber for a particular Family. In other words, given a Family, an ApartmentDirectory should be able to return the apartmentNumber where they live.

Two different types of errors might occur during the execution of ApartmentDirectory methods. In the interest of time, you must handle only one of these two types of errors - your pick. You can assume that the user will be well behaved and not generate the other. You should use the typical Java mechanism to ensure that if the error condition occurs, the affected method does not return normally, but instead inform the caller of the condition.

• FamilyNotFound, if the user attempts to getTheApartmentNumber for a Family that is not recored within the ApartmentDirectory.
  
  
• InvalidApartmentNumber, if the user attempts to recordAFamily as residing at a non-existent apartment number.