Chapter 9, Problem 11E

Creating a class “RoomCounterAssert.java”:

• Import required package.
• Define the class “RoomCounterAssert”.
  • Declare a private variable “countPeople”.
  • Define a default constructor and initialize the value.
  • Give function definition to “addPerson ()”.
    • Increment the value of “countPeople”.
  • Give function definition to “removePerson ()”.
    • Create an assertion with condition “countPeople > 0”
    • Decrement the value of “countPeople”.
  • Give function definition to “getcount ()”.
    • Return the value of “countPeople”.
  • Define the “main ()” method.
    • Create an object “rc” for the class “RoomCounterAssert”.
    • Get and print the value of count by using the function “rc.getCount ()”.
    • Add three persons by calling the function “addPerson ()” three times.
    • Get and print the value of count by using the function “rc.getCount ()”.
    • Remove two persons by calling the function “removePerson ()” two times.
    • Get and print the value of count by using the function “rc.getCount ()”.
    • Remove one person by calling the function “removePerson ()” one time.
    • Get and print the value of count by using the function “rc.getCount ()”.
    • Again remove one person by calling the function “removePerson ()” one time.
    • Get and print the value of count by using the function “rc.getCount ()”.

Program:

RoomCounterAssert.java:

//Define a class

public class RoomCounterAssert

{

    //Declare a private variable

    private int countPeople;

    //Define a default constructor

    public RoomCounterAssert()

    {

        //Assign 0

        countPeople = 0;

    }

    //Give function definition to add person

    public void addPerson()

    {

        //Increment the variable

        countPeople++;

    }

    //Function definition to remove person

public void removePerson()

    {

        //Create an assertion

        ass...